[shell] Make menus forget what you're hovering on between activations
[world] Add some vision walls in test3
[geo] Fix bug when the camera area is constrained to infinitely thin.
[world] Fix some wall associations
[util] Allow operator / (Vec, Vec)
[ent geo] More sophisticated vision system (buggy currently)
[ent geo] Fix new vision system
Merge branch 'forrealz' of github.com:quietfanatic/rata into forrealz