Doors

[aawilson]

They open! They close! Should be two types:

1. Doors like regular roguelikes. These are probably understood to be opened by proximity sensors or hand panels or something (we'll want to specify exactly which later as the interactions become complex). They'll either open when you move into them, or when you're next to them--I haven't decided.
2. Bulkhead doors that only open from control panels, and empty into the vastness of space.