Feature: Scalable OpenTTD TrueType font made by Zephyris.

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

Fix #10993: Crash log when font caches not initialised (#11024)

See also: #10836

Fix: Don't rely on static initialization to set up sprite font caches.

The order of static initialization is undefined, so this can cause initalization
before relevant caches are initializations.

Change: Rename some freetype things to fontcache.

The font cache supports more than just FreeType as a font provider, but still used freetype in some naming.

This now uses more suitable terms.

Remove: logically dead code from font cache

The outer if statement checks for 'aa' being false, so within the inner
statements anything checking aa will have a known result and the other
branch from there will be dead code.

Codechange: make explicit that virtual functions in a con/destructor are resolved statically

This as during construction the sub class has not been initialized yet, and
during destruction the sub class has already been destroyed, so the overriding
virtual function would be accessing uninitialized data.

Codechange: Scale sprite font height once on init instead of every call to GetHeight().

Scaling is not expensive, but it does not change either, and this avoids the need for a virtual method call. This cascades back to all GetCharacterHeight(FS_xxx) and FONT_HEIGHT_xxx calls.

Cleanup: Use GetDefaultFontHeight() call instead of direct access.

This makes this part of font size setup in FreeTypeFontCache consist with OSX and Windows variants.

Codechange: Apply coding style (#8640)

* Fix: Missing or needed spaces

* Codechange: Remove space

* Codechange: Remove space

* Codechange: More missing spaces

* Codechange: Missing spaces

* Codechange: Remove space

* Codechange: Remove space

Add: use our search-paths to find fonts based on relative filenames too

This allows "small_font = ./myfont.ttf", with "myfont.ttf" located
in "~/.openttd".

Add: support for emscripten (play-OpenTTD-in-the-browser)

Emscripten compiles to WASM, which can be loaded via
HTML / JavaScript. This allows you to play OpenTTD inside a
browser.

Co-authored-by: milek7 <me@milek7.pl>

Codechange: Replace SmallPair with std::pair.

std::pair is already the smallest possible pair, and it already handles non-POD types correctly.

Add: [Win32] GDI engine for font glyph rendering as a replacement for including FreeType.

Building with FreeType is still possible and will take precedence over the GDI renderer, but
the project files don't include FreeType anymore by default. Combining GDI rendering with ICU
text layout is untested.

Codechange: Refactor the Freetype font cache into a generic part that does not depend on Freetype and into one that does.

This makes it easier to add other TrueType font rendering engines.

Feature: Add option to adjust font size separately from GUI size. (#7003)

Adds an option in the "Game Options" next to "Interface Size" called "Font Size". Available options are normal, double, and quad.

Add: [OSX] Text layout using the native CoreText API.

By default, the native API will be used instead of ICU, but if ICU is
forced in using configure, it will take precedence.

Add: [Win32] Text layout using the native Windows Uniscribe library.

Uniscribe is sometimes producing different results compared to ICU, especially
when RTL and LTR content is mixed. Comparing the results to other programs
(like editors or web browsers) leads me to believe that the result are at least
not worse than ICU and possibly better.

(svn r23582) -Fix [FS#4870]: add missing characters for certain languages and the large font
-Codechange: don't remove large font glyphs because they are broken in the original font, just fix them up in openttd.grf using action A
-Change: make extra characters more consistent with the original font
All by PaulC.