Marathon Run adjustments

See merge request STJr/SRB2!1048

Fix models that use sprite textures

See merge request STJr/SRB2!1049

Bruh Core Zone 2

See merge request STJr/SRB2!1047

Introduce a live event backup penalty for non MA_INGAME runs, since the change to saving time causes problems for this.

Hopefully fix the issue, which I can't recreate, of live event backups being created even if they shouldn't.

Add a small amount of extra info to the Evaluation screen for Marathon Mode, on request from multiple runners.

Fix the issue where custom exits with skipped intermission screens (notably, Black Core Zone 2 and 3) would cause the game to softlock when playing on a save file, or with a live event backup.

Restore SKINCOLOR_SUPERGOLD1-5 changes from 2.2.3

See merge request STJr/SRB2!1042

Fix custom skincolors being fullbright & signpost backgrounds using incorrect color shades

Closes #179 and #182

See merge request STJr/SRB2!1043

Whose idea was it to make the aPNG speed 1/2x by default?!

See merge request STJr/SRB2!1044

2.2.5 preparation

See merge request STJr/SRB2!1039

Remove Software tricks

See merge request STJr/SRB2!1036

Fix autoexec file trying to set netvars when joining from command-line

See merge request STJr/SRB2!1040

M_RATHON header text

See merge request STJr/SRB2!1041

Fix timeout

See merge request STJr/SRB2!1038

The credit

See merge request STJr/SRB2!1033

Knuckles tweaks

See merge request STJr/SRB2!1030

Allow macOS builds to be launched through Steam

See merge request STJr/SRB2!996

Create a slightly more dynamic, optional frame delay system to show off your terrible hardware with

See merge request STJr/SRB2!1023

Take 2: Fix Old Brak missiles + add pw_ignorelatch

See merge request STJr/SRB2!1006

Use levelflat->name instead of flatname

See merge request STJr/SRB2!1024