Players have to wait 5 minutes between dying as a mouse and respawning as a mouse. Global variable mouse_respawn_time determines the respawn time in minutes.

Mice can no longer open airlocks.

Mice can no longer strip items from humans

Mice can no longer put other creatures into disposal units (though they can still climb into disposal units)

Message for when mice crawl into vents removed. Mouse nibbling message only displayed to observers half the time.
Some uses of ismouse() replaced with isanimal()

world.time used to calculate mouse spawn timer.

Spawn timer now applies to being killed via splat().
Added var/small to mobs, which currently only handles if they can open airlocks. This replaces the use of ismouse().
Merge pull request #2376 from RavingManiac/master

Stopped the mousepocalypse