Make vehicle car doors generate open instead of closed 25% of the time.
Minor update of overmap.cpp

easier bool functions, reduced number of type mismatch warnings
Changed leather patch volume to 1.

Currently rags are volume 1, fur is volume 1, plastic chunks are 1,
scrap metal is 1, kevlar plates are 1, yet leather patches are volume 2.
When you cut a volume 1 fur into leather it becomes a volume 2 object,
so this fixes that and makes leather consistent with the other basic
crafting resources.
Merge mysterious opened vehicle doors, overmap predicate cleanups, and leather patch volume harmonization.