Add support for Arabic/bidirectional text

[Daaaav]

Changes:

As mentioned in https://github.com/TerryCavanagh/VVVVVV/issues/829#issuecomment-1875175582, we're aiming to get Arabic in for 2.4.0, which is a language that needs some significant technical changes! Luckily those happened fairly quickly and painlessly.

• This adds a new submodule, SheenBidi, which is a pretty lightweight, compatible (C90 even) and low-dependency library for bidirectional text support.
• Arabic letter reshaping was written with guidance of this code: https://github.com/TerryCavanagh/hx_arabic_shaper
• Arabic ligatures are also converted, from a table given by Montassar (one of our Arabic translators)
• Automatic wordwrapping works properly without further changes (Arabic uses spaces, and we do convert the logical ordering to visual ordering)
• To provide a fast path when printing text for LTR languages (and less chance of unexpected breakage of existing content), all the bidi and reshaping machinery will only run for a printed string if one of the following is true:
  • Printing interface text while the current language has the <rtl> property set
  • Printing custom level-specific text while the level has the <rtl> property set
  • The string contains characters in Unicode blocks for the Arabic or Hebrew alphabets, or directional control characters (like the famous U+202E).
• The mentioned <rtl> properties also control things like right-alignment in textboxes
• An Arabic font (made by Montassar) is added as font_ar (this is an 8x10 font, and it doesn't have Latin characters itself, so I copied 00-FF from Space Station just so we don't duplicate everything, just the important stuff)
• Changes made to print flags:
  • PR_FONT_IDX(idx) now has two arguments: PR_FONT_IDX(idx,rtl). Since PR_FONT_INTERFACE (0) sets the RTL printflag based on the current language, PR_FONT_LEVEL sets it based on the current level, and PR_FONT_8X8 sets it disabled, PR_FONT_IDX requires you to provide whether RTL mode should be enabled. This was always just a simple filling in based on information we had at hand anyway since we got the font index from either the language metadata or level metadata.
  • PR_RTL_FORCE exists now (it's just set internally by PR_FONT_IDX)
  • PR_RTL_XFLIP lets you mirror the X axis specifically in RTL languages, so the left border is 320 and the right border is 0, and invert the meaning of PR_LEFT (0) and PR_RIGHT. Most of the time this is not necessary, it's just for stuff where a label is followed by a different print, like "Font: " followed by the font name, time trial time displays, etc. This is also used for the menus.
• Just like the setfont(font) scripting command was added to change <font> during playtime, in parallel, now that <rtl> was added, I added the scripting command setrtl(on/off).

Whew, that was everything I think! Time for some screenshots:

A random Arabic sentence:

Lots of ligatures and right-alignment:

A right-to-left menu, and user input:

https://github.com/TerryCavanagh/VVVVVV/assets/44736680/bdf666f7-adbc-46d7-b28a-51e03f6612c4

Legal Stuff:

By submitting this pull request, I confirm that...

• [x] My changes may be used in a future commercial release of VVVVVV
• [x] I will be credited in a CONTRIBUTORS file and the "GitHub Friends" section of the credits for all of said releases, but will NOT be compensated for these changes

[Daaaav]

Just force-pushed a whole bunch of fixes and improvements - everything mentioned in the comment above and on Discord, as well as some other things:

• Fixed controller button directions in menus
• Fixed reshaping and ligatures not always working properly because I forgot to include run offsets
• Fixed centering and padding in textboxes
• Mirrored some more interfaces that needed to be (like time trial results and game complete)