Codechange: Use `GetVisibleRangeIterators()` in more places. (#12190)

This replaces more first/last index calculation, along with indexed array/vector access, with iterator access instead.

Codechange: Remove direct access to _colour_gradient.

Access is now through GetColourGradient, which ensures parameters are in range.

Codechange: Make all NWidgetPart arrays constexpr.

This ensures that the arrays are not created at runtime and prevents using non-constexpr values.

Codechange: Use vector/unique_ptr inside widget containers.

This replaces a C-style double-linked-list which required all widgets
to have next/prev pointers, and removes the need for manual pointer management.

Codechange: Replace mishmash of types for widget index with WidgetID.

Indices were stored as int, but often passed around as uint/uint8_t and casts.

Now they should all use WidgetID.

Codechange: Use std::map to provide indexed widget access.

This removes the need to determine the biggest widget index and replaces C-style memory handling.

Codechange: Remove deferred nested_array initialization path. (#11640)

Having two ways (`FillNestedArray` and `SetupSmallestSize`) to initialize
`Window::nested_array` introduces confusion.

Instead, make `FillNestedArray` the canonical way, always call it, and remove
init_array from `SetupSmallestSize`.

Change: Hide bevel for resizeable sparse layout windows. (#11572)

When clicked, the button is still highlighted to show that it is active.

The bevel is controlled with widget_data by RWV_SHOW_BEVEL or RWV_HIDE_BEVEL values.

Fix #11352: Draw all network server info as multiline strings. (#11567)

This also allows the 'header' (which is not actually a widget) to grow
as necessary to fit the server name.

Codechange: Optionally allow passing state to GUIList sorter function.

GUIList sorter functions can currently only use global state, which makes per-window-instance sorting difficult.

Codechange: Remove FONT_HEIGHT_... macros. (#11481)

These make it look like we're dealing with a constant, but actually each is a call to `GetCharacterHeight(...)`.

Codechange: Add __FILE__/__LINE__ of WindowDesc to WindowDesc.

This is to allow unit-tests to produce more useful output.

Codechange: Assign/StoreSizePosition x/y can be negative. (#11416)

AssignSizePosition is used with negative values when an NWidgetMatrix is
scrolled, but they were passed as unsigned and then stored as signed.

Widget pos_x/pos_y were already made signed.

Codechange: Use unified NWidgetContainer methods instead of duplicating.

Most NWidgetContainer derivatives implemented Draw() and GetWidgetFromPos()
the same way. Move this these to NWidgetContainer itself to avoid repeating.

Codechange: Hide multiplayer headers by setting width to zero.

Zero-width is how widgets are hidden elsewhere.
This removes the need for an extra array to lookup if a header is hidden.

Codechange: Avoid emplace_back(new()) into a unique_ptr. (#11384)

This could theoretically leave an unmanaged pointer in certain circumstances, and directly using
make_unique shows intent.

Fix: Treat closing network relay window as a choice of "No".

Issue ConnectFailure when closing the window if the relay request is
considered unhandled.

Codechange: Use begin/end of nwidget parts of begin/length.

This simplifies processing nwidget parts as, unlike the remaining length, the pointer to the end of the list never changes. This is the same principle as we use(d) for tracking end instead of length for C-style strings.

And this removes 160~ instances of the lengthof() macro.

Codechange: automatic adding of _t to (u)int types, and WChar to char32_t

for i in `find src -type f|grep -v 3rdparty/fmt|grep -v 3rdparty/catch2|grep -v 3rdparty/opengl|grep -v stdafx.h`; do sed 's/uint16& /uint16 \&/g;s/int8\([ >*),;[]\)/int8_t\1/g;s/int16\([ >*),;[]\)/int16_t\1/g;s/int32\([ >*),;[]\)/int32_t\1/g;s/int64\([ >*),;[]\)/int64_t\1/g;s/ uint32(/ uint32_t(/g;s/_uint8_t/_uint8/;s/Uint8_t/Uint8/;s/ft_int64_t/ft_int64/g;s/uint64$/uint64_t/;s/WChar/char32_t/g;s/char32_t char32_t/char32_t WChar/' -i $i; done

Feature: opt-in survey when exiting a game

On first start-up, the game will ask if you want to participate
in our automated survey. You have to opt-in, and can easily opt-out
(via the Options) at any time.

When opt-in, whenever you exit a game, a JSON blob will be send
to the survey server hosted by OpenTTD. This JSON blob contains
information that gives a global picture of the game just played:
- What settings were used
- How many humans vs AIs
- How long the game has been played
- Basic information about the OS / CPU

All this information is kept very generic, so there is no
chance we send private information to our survey server.
Nothing in the JSON blob could identify you as a person; it
mostly tells about the game played. At any time you can see
what the JSON blob includes, by pressing the "Preview Survey
Results" button in-game.

Codechange: Add and use GetScrolledItemFromWidget to get a list item.

This function returns an iterator, either to the selected item or the
container's end.

This makes handling the result more robust as indices are not used.

Codechange: Scrollbar methods now accept size_t.

This clears up a lot of casts from size_t to int.

Codechange: migrate all Window-related timers to the new framework

This means we also say goodbye to GUITimers.

Change: Make all dropdown lists extend width if necessary.

This removes the auto_width parameter from ShowDropDown(At).

Codechange: introduce GetMainWindow() to properly account for nullptr checks

Some nullptr checks have been removed as they were not triggered with nullptr
with the null video driver and in dedicated server mode.

Change: Standardize progress bar layout.

Progress bars are drawn differently depending on when it was added, with
different layouts and sizes.

This change adds a standard padding size to use, and makes all progress
bars visually similar, with scaled padding.

Change: Use Rect helpers for widget drawing.

This replaces repetitive and sometimes unwieldy use of constants.

Cleanup: Tweak panel layout of Online Players window.

This ensures panel borders not hidden behind other widgets.

Fix: Online Players list mouse hover behaviour.

Hover highlight was visible even if the mouse pointer was in a different
window, and the window refreshed itself every frame if the mouse pointer
was not over its matrix widget.

Resolved by using OnMouseOver() instead of OnMouseLoop(), and only
redrawing if the hover position has changed.

Codechange: Template DoCommandP to automagically reflect the parameters of the command proc.

When finished, this will allow each command handler to take individually
different parameters, obliviating the need for bit-packing.

Add: [Network] Keep the refresh button in lowered state while refreshing (#9600)

This gives user visual feedback that the refresh is still pending, and
prevents people from clicking again and again thinking nothing is
happening. This is especially true for connections that fall back to
TURN, as that takes a few seconds to kick in.

Additionally, prevent clicking on the button again while a refresh
is pending. This is only delaying a successful result.

Fix: [Network] show query errors in the server listing instead of error popup (#9506)

When you are query several servers at once, it is rather unclear
for which server you got a popup. Instead, show any errors on the
server itself.

This is only true for the query-part. Joining a server still gives
an error popup to tell you about any issue.

Fix: [Network] crash when last-joined server that is no longer available (#9503)

If you update the server-list while not having last-joined selected
and it is no longer available, the game crashed.

Fix #9492: show for what server a relay session is being created (#9494)

Currently it says "the server" which is a bit ambigious. Be more
specific.

Feature: make "join game" button join the game, instead of first showing a lobby window (#9467)

Nobody really paid attention to the lobby window, and it completely
missed its purpose. Most people don't even wait for companies to
show up, but just hit "New Company".
This in turn means people create a lot of unneeded companies, while
they "just want to watch the game" or join another company.

Instead, "Join Game" now just joins the game as spectators.

Fix 508e465b: network servers didn't show invite-code / connection-type in Online Players GUI (#9478)

The selector selects the first widget, which by accident was now only
the server visibility.

Change: remove the ability to control "max spectators" (#9466)

Soon we will make "join game" join the game as spectator first,
so limiting the amount of spectators makes no sense anymore in
that context. Not sure it ever did make sense.

Feature: allow the use of TURN to connect client and server together

TURN is a last resort, used only if all other methods failed.
TURN is a relay approach to connect client and server together, where
openttd.org (by default) is the middleman.

It is very unlikely either the client or server cannot connect to
the STUN server, as they are both already connected to the Game
Coordinator. But in the odd case it does fail, estabilishing the
connection fails without any further possibility to recover.

Add: inform clients what game-script a server is running (#9441)

Co-authored-by: The Dude <thedude@novapolis.net>

Add: allow setting your server visibility to "invite-only" (#9434)

In this mode you do register to the Game Coordinator, but your
server will not show up in the public server listing. You can give
your friends the invite code of the server with which they can
join.

Feature: join servers based on their invite code

This removes the need to know a server IP to join it. Invite codes
are small (~7 characters) indentifiers for servers, which can be
exchanged with other players to join the servers.

Codechange: [Network] Remove overload on NetworkValidateClientName

Rename the zero-parameter NetworkValidateClientName to NetworkValidateOurClientName to make it clearer it is performed on our client name, and to make it a non-overloaded function to aid with the variant being added a few commits later

Fix #9362: Hover in online players window was slightly too big (#9364)

This causes graphical glitches at the bottom of the window.