GLIBCXX_DEBUG fix: Don't walk off the front of the iterators when crafting using the first item.
Rework fix to address comments by BevapDin.
Whoops, actually need to check the precondition ourselves when doing stepping manually.
Aaand now I'm crashing making arrows. Do the same treatment for inventory::use_charges().
GLIBCXX_DEBUG: If we run out of hotkeys for construction, print space instead of reading arbitrary data..
GLIBCXX_DEBUG: Don't use veh_part for two things - causes read of invalid element.
GLIBCXX_DEBUG: Recompute indices every time in case armor was destroyed in previous loop iterations.
Rename veh_part to cargo_part in game::pickup.
Merge index handling cleanups.