Fix addons with custom gamedata not loading

Closes #473

See merge request !1427

Fix unused variable warning when USE_APNG is not defined

See merge request STJr/SRB2!1343

Fix sigsegv caused by bad target check in A_Custom3DRotate

See merge request STJr/SRB2!1430

Fix OpenGL V_DrawCroppedPatch (Fixes #452)

Closes #452

See merge request STJr/SRB2!1412

(Apparently Kart made this exact fix 2 years ago and it was never backported?)

Fix compile warning on Windows

See merge request !1426

More final tweaks for 2.2.9 I guess

See merge request !1417

Papersprite dropshadows no longer askance

Closes #409

See merge request !1408

Fix a few renderflags oversights in OpenGL

See merge request !1422

Fix for #422

Closes #422

See merge request !1425

Remove misplaced SetShader call in CompileShaders (Fixes #402)

Closes #402

See merge request !1423

Use double precision in R_StoreWallRange sloped seg culling calculations (Fixes #434)

Closes #434

See merge request !1424

Print a backtrace when SRB2 crashes in a Unix-like environment.

See merge request !1288

Fixes culling issues in CEZ2 skybox

Check if GME_VERSION is defined.

See merge request !1372

Fix CA_BOUNCE height when flipped (Fixes #428)

Closes #428

See merge request !1373

Disable pausing during score screens in marathon mode

See merge request !1416

Fix translation colormap cache rebuilding using the old translation enumerations (fixes #443, #449, #459)

Closes #443, #449, and #459

See merge request !1421

Fix thing scale mismatch in R_DrawVisSprite. (Fixes #458)

Closes #458

See merge request !1420

Revert "Merge branch 'player-speed' into 'next'"

Closes #466 and #471

See merge request !1418

This was causing a buffer underwrite too. Lovely.

Fix "implicit declaration of function 'DEH_TableCheck'" warning

See merge request !1419

Nice UDB config there, SRB2.

See merge request !1354