This reverts commit b2d693a5.

So they don't mess with shell scripts that expect SRB2 to exit when it crashes (like most other programs)

Checks if P_TryMove would succeed without actually moving.

MT_NULL spawning, not cool bro.

- Resetting portalcullsector fixes the major visual glitches

- Using 32 bits for nummasks and i fixes crashes when rendering lots of portals

This reverts commit 13778247.