More customisable title card

See merge request !552

Wipe styles cleanup

See merge request !525

The "SRB2" directive, for warning if a SOC isn't compatible

See merge request !551

OpenGL GIF movie recording

See merge request STJr/SRB2!549

Fix model texture blending

See merge request !546

Init MUSICDEFs regardless of music state

See merge request !532

Fixed missing break in offset handling for horizontal springs

See merge request !571

Handle signals correctly on linux

See merge request !530

Hack P_SpawnMapThing into tiny little pieces

See merge request !564

Netarchive compare changes

See merge request !563

Refactor P_SpawnHoopsAndRings

See merge request !562

P_SpawnMapThing(): Separated the giant post-Lua hook switch-case statement into its own function, and separated some of the larger cases into their own function as well