v0.0.22: Playtest fixes

Doors: a big [T] OPEN DOOR / CLOSE DOOR prompt shows when you face a Stone Door, even with a gun in hand, and T works on the selected door in the commander view
The Hollow: you use a station by looking at it from up close - no more using it with your back turned or from odd spots, and never through rock
UNSTUCK in the pause menu: hold still for 5 seconds to return to your Base (cancelled by moving or taking damage; not while carrying a Heartstone or overloaded)
No more falling out of the world: the map edges past the lanes are walled off, and anyone who does fall is put back at the Base
You can no longer stand on walls, guns or other buildings - you slide back off to the side you came from