Updated some backgrounds for the following stages:
Hexane Act 4 (new main bg, updated arena)
Tritium Act 3 (updated water in bg)
Tritium Act 4 (new main bg)
Nitra Act 1 (new main bg)
Nitra Act 4 (updated colors for both main and arena)
An endgame fight's second phase
The doors that lead into a boss arena now are colored based on the level they appear in (doesn't affect central district act 4).
Divas now have a dedicated transition effect into phase 2 of their fights. Starting phase 2 from a checkpoint will skip this transition. But it should be cooler than the screen simply fading out.
Fixed issue where checkpoints didn't function in a lategame stage in an alternate gamemode.
Fixed issue where player could get trapped in a lategame stage in an alternate gamemode.