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.

Change: base autosaves intervals on real time (instead of game time) (#10655)

There are two fundamental issues with autosave:
- When fast-forwarding, it saves way too often
- When paused, it never saves

Both makes no sense. Autosaves are meant to prevent you from
accidentally losing your work. The emphasis on "your" work.

To solve both issues, the autosave now works on real time. You
can select every 10 / 30 / 60 / 120 minutes, which are similar to
what the setting was in game-months.

When you pause, autosaving will stop. Unless you make any change
to the game; then it will continue to make autosaves, even so
the game is paused. Unpausing / pausing resets this mechanism.

Fix: thread safety issue during exiting the game (#9380)

_exit_game is read by the draw-thread to know when to exit, but
most of the time written by the game-thread.

Fix #6598: Prevent invalid memory accesses when abandoning a join from within a network game

One could join a network game from within an already running network game. This would call a NetworkDisconnect, but keeps the UI alive. If, during that process the join is aborted, e.g. by cancelling on a password dialog, you would still be in your network game but also get shown the server list.
Solve all the underlying problems by falling back to the main UI when (re)connecting to a(nother) server.

Add: make modal windows update more smooth

Basically, modal windows had their own thread-locking for what
drawing was possible. This is a bit nonsense now we have a
game-thread. And it makes much more sense to do things like
NewGRFScan and GenerateWorld in the game-thread, and not in a
thread next to the game-thread.

This commit changes that: it removes the threads for NewGRFScan
and GenerateWorld, and just runs the code in the game-thread.
On regular intervals it allows the draw-thread to do a tick,
which gives a much smoother look and feel.

It does slow down NewGRFScan and GenerateWorld ever so slightly
as it spends more time on drawing. But the slowdown is not
measureable on my machines (with 700+ NewGRFs / 4kx4k map and
a Debug build).

Running without a game-thread means NewGRFScan and GenerateWorld
are now blocking.

Change: change console command "restart" and add "reload"

The current "restart" command is now called "reload", as that is
what it does.
The old "restart" command is now called "restart", as that is what
it did.

As this has not been in any official release yet, this shouldn't
harm any kitten.

Change: [Linkgraph] Pause the game when linkgraph jobs lag (#6470)

Check if the job is still running two date fract ticks before it is due
to join, and if so pause the game until its done.
When loading a game, check if the game would block immediately due to
a job which is scheduled to be joined within two date fract ticks,
and if so pause the game until its done.
This avoids the main thread being blocked on a thread join, which appears
to the user as if the game is unresponsive, as the UI does not repaint
and cannot be interacted with.
Show if pause is due to link graph job in status bar, update network
messages.
This does not apply for network clients.

Add: save openttd.cfg immediately on changing a setting (#8358)

Formally it was only done on exit. This means that if it crashes
changes in settings were not stored. This is often rather
frustrating. Additionally, targets (like emscripten) where people
are unlike to use "Exit Game", will never see their configuration
stored.

The drawback is that on every setting change there is some minor
I/O of writing the ini file to disk again.

Feature: Improve restart command

When the restart command is issued, a normal map is always spawned.

This improvement takes into account the current state of _file_to_saveload to check if a savegame/scenario/heightmap was previously loaded, and loads the same resource again.

(svn r16242) -Codechange: rework pausing
-Fix [FS#2864]: autopause and manual pausing conflict with eachother
-Fix: new game + pause on new game + autopause make the game not unpause on the first join

(svn r11533) -Codechange: Rename some unclear clear_x prices member names.
While at it, remove one unused entry on the clear_price_table array.
It is based on ground type, and the unused one was referencing a non existing one.

(svn r11399) -Feature(ette): transparency settings can now be saved and thus remembered.
-Codechange: Wrap all transparency settings in accessors, hiding the implementation
-Change: Clicking "transparent building" menu will toggle Houses And Trees only. The other options can be used in the transparency gui.
Initial patch by Smatz (FS#1349), with some rework by BigBB and your humble servant.

(svn r11005) -Codechange: move the tiletype specific terraforming checks to the functions for those tile types.
-Codechange: barren the rail grounds on terraforming.

(svn r10762) -Codechange: Change enum StringIDEnum { to static const StringID = for
each STR_ entry. This avoids the need for a cast to StringID in some
places and thus better type-safety.

(svn r10258) -Codechange: as we are now using int64 all over the place, it's better to use int64 variables in the string generating too instead of packing them into two int32s.
-Fix: some displays of money were wrong.

(svn r9779) -Feature: Add the possiblity to choose different road patterns for towns to use.
Possible patterns are :
No Road (not available in scenario editor)
Original (for the nostalgics)
Better Roads (same as original, but based on distance of 2 tiles instead of one)
2x2 grids
3x3 grids
Patch by skiddl13