fixing that problem where vehicles evaporate

Why does this fix it? I'm not sure exactly :/
fixing skills rusting almost every turn.
Merge pull request #28 from zpmorgan/overmap-boundary-mapgen

fixing that problem where vehicles evaporate
Merge pull request #29 from zpmorgan/skill-rust

fixing skills, which were rusting almost every turn.
Merge pull request #30 from zpmorgan/master

bounds checking for veh_exists_at.
caching player rendering conditions

rather than crawling inventory for unlikely items for each rendered tile.