Feature: Scalable OpenTTD TrueType font made by Zephyris.

This uses the normal variant for the small font, not the all-caps version.

Codechange: Replace pointer to Sprite array with reference to SpriteCollection. (#11580)

Add `SpriteLoader::SpriteCollection` type which is an array of `SpriteLoad::Sprite`.

This removes the ambiguity of what `SpriteLoader::Sprite *` is pointing to,
and cleans up mismatches using both dereference -> and array access [] for the
same object.

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: Pass face index as font os_handle for FreeType fonts. (#11073)

This allows fallback font detection to test the specific face within the
font rather instead of only the first.

Codechange: Remove Freetype bits on Win32/OSX. (#10960)

These platforms have their own specific font rendering.

Feature: drop ICU-lx in favour of directly interfacing with harfbuzz

This means we have RTL support again with ICU 58+. It makes use of:
- ICU for bidi-itemization
- ICU for script-itemization
- OpenTTD for style-itemization
- harfbuzz for shaping

Codechange: Make SpriteType, CargoSortType, SourceType and ScriptType enum classes. (#10663)

This avoids a (soft) namespace conflict between the four ST_* enums.

Codechange: address CodeQL issue "Multiplication result converted to larger type" (#10306)

Most are very unlikely to ever be triggered in our codebase; two
stand out: linkgraph and money cheat. Those, potentially, could
wrap earlier than expected.

Feature: Variable GUI scale.

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