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: remove queue_wrap / last_position from mouse movement

No backend uses it anymore, so also no longer any need to support
it.

Codechange: C++-ify the Layouter and related functions

They all now access a std::string_view, instead of a "const char *"
or std::string (in some cases).

Additionally, GetCharAtPosition and friends now return an index
instead of a "const char *", as it makes for a more clear interface.

Feature: Variable GUI scale.

GUI scale is now variable from 100% to 500%, and no longer restricted to
powers-of-2.

Change: [OSX] Allow touchbar usage on all supported OS versions.

Touchbar support was introduced in 10.12.2. There's no need to limit
support to 10.15+, as the convenience class NSButtonTouchBarItem is
easily replicated.

Codechange: [OSX] Use more exact enum names where introduced with the 10.12 SDK.

The enum values still have the exact same numerical values, but the 10.12
SDK introduced more explicit names (e.g. like NSEventTypeApplicationDefined
instead of NSApplicationDefined) for several enum constants.
Use them when available.

Codechange: [OSX] GameLoop is really more like MainLoop

MainLoop() is used to bootstrap OSX, where later a callback is
done to GameLoop() to execute OpenTTD. All other video drivers
don't need that, so what is in GameLoop is in MainLoop for all
other drivers. This is rather confusing. So, instead, name
GameLoop MainLoopReal to be more in sync with the other drivers.

Codechange: [OSX] Split drawing into its own subview.

This allows the drawing backend code to be independent
of any event or command handling.

Fix: [OSX] Quitting in fullscreen mode would loose the original window size.

This replicates the behaviour on e.g. Windows, which saves the original window size.

Codechange: [OSX] Re-arrange the OSX video driver code by combining all drawing code and moving the window/event handling to a different file.

This is just a code move/rename, not a functionality change.