Stopped the mousepocalypse

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)

Messages for when mice hide and crawl into vents removed. Mouse nibbling message only displayed to observers half the time.