Backports the text rendering code from 1.6 to 1.5.
Done by starting with the current master's engine/render/text_render
and backporting things as-needed until it worked.
CLX rendering and text input handling are also backported as part of
this change.
Original Blizzard encoder is slightly less optimal than our encoder.
While size in RAM in less of a concern for the non-`UNPACKED_MPQS`
build, smaller files are faster to render.
Savings for unpacked and minified MPQs:
* diabdat.mpq: 918,311 bytes.
* hellfire.mpq: 313,882 bytes.
Example player graphics (note that only a few are loaded at any given time for single player):
* diabdat/plrgfx/warrior/: 366,564 bytes.
Example monster graphics savings:
* diabdat/monsters/skelbow: 5,391 bytes.
Based on the implementation from https://github.com/diasurgical/devilutionx-graphics-tools/pull/6
Gleb Mazovetskiy