Fix a dumb typo of luaL_checklstring i made whoops

See merge request !1266

Make several Lua global variables writable.

See merge request !1233

Improved sprite sorting against 3d floors

See merge request !1235

Can't use gz/gzt because there is no transformation to make those work
differently for splats.

Flame Shield & Thunder Shield Adjustment (Closes #363)

Closes #363

See merge request !1220

Made height/spinheight and height change values in replays more accurate

See merge request !1241

Make the replay camera follow the player

See merge request !1243

Remove unused music type enums

See merge request !1253

Uncap palette lump palettes & allow flashpal palettes to display during pause

See merge request !1255

Echo filenames when compiling without ECHO=1

See merge request !1260

New sprite features

See merge request !1257

Update R_DrawFloorSprite_NPO2_8 and R_DrawTranslucentFloorSprite_NPO2_8 to have the lastest NPO2 optimizations

Use SDL version of executable icon at runtime on macOS

See merge request !1250

UDMF: Multitag support

See merge request !1097

Expose more music functions to Lua

See merge request !1230

Don't let Lua set cvars that have CV_NOLUA

See merge request !1245

Fix potential crash with precipitation in OpenGL

See merge request !1249

Reallow P_MobjSpawn to change the scale of objects spawned from mapthings

Closes #328

See merge request !1251

Remove direct definition for D__USE_MINGW_ANSI_STDIO, as the latest standards consider this to be deprecated.