Codechange: Make all NWidgetPart arrays constexpr.

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

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: 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: 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

Codechange: Use GetScrolled(Row/Item)FromWidget in more places.

In many instances the clicked row position is 'manually' calculated
instead of using the GetScrolledRowFromWidget helper function, with
variations on checks. Replace with the two helpers where possible.

Change: include fmt.h C++ headers in stdafx.h

This to prevent compilation issues between runs with and without precompiled
headers. Also remove the headers from the rest of the code base as they are
not needed there anymore, although they do relatively little harm.

Feature: Separate rail/road and sea/air velocity units, and add knots. (#10594)

This is achieved by packing vehicle type along with the velocity so that
the string system can decode and pick the appropriate unit.

Fix: bad oddness checks

Modulo on a signed number returns negative values for negative values, so
i % 2 == 1 will only return true for positive odd numbers, whereas i % 2 != 0
returns true for both positive and negative odd numbers.

Change: Use Rect helpers for widget drawing.

This replaces repetitive and sometimes unwieldy use of constants.

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.

Codechange: Make TileIndex a "strong" typedef to give it a distinct type.

This is accomplished by changing it to a single member struct with the
appropriate operator overloads to make it all work with not too much
source modifications.

Codechange: remove unneeded comparison and casts

Division by resize_y is already yielding an unsigned number, so when clicking in the WD_FRAMERECT_TOP you would already get a huge value, so sel would never be negative. So, leave sel an unsigned number and remove the <= check.

(svn r21933) -Codechange: Split cur_order_index into cur_auto_order_index and cur_real_order_index to keep track of the current real order in an unambiguous way.
-Fix [FS#4440]: Automatic orders behave now stable wrt. service orders and are not added or removed depending on the need of servicing.
-Fix: Various other issues with automatic orders, e.g. vehicles getting stuck with "no orders" when there are automatic orders at the end of the order list.

(svn r20453) -Codechange: Remove direct accesses to Window::hscroll, vscroll and vscroll2.
Note: All windows get individual members with the same names, which are initialised via Window::GetScrollbar(). This caching is not required at all, but simplifies conversion.