use json to store and load status of convertible vehicles
add back support for old format of hp of folding bicycle
add vehicle facing indicator option
int -> float
switch checks
Removes welding-goggle requirement for disassembly

Since you don't actually weld anything when disassembling, shouldn't
need the goggles at all, I'd imagine.

Fixes vehicle typo as well (wouldn't compile w/o fix, sorry).
Merge folding bike refactor, vehicle facing, and welding adjustment.