use compatible trap.id
trap: implement string id, make int id dynamically allocated, nuke enum
and replace with int for pre-existing functions, add string based trap set/get
methods.
tiles: nuke static trap_names in favor of trapmap
mapbuffer save/load: auto translate from legacy / differing traps.
vehicle: convert the game's only trap_id switch statement to if/else/if/else of doom
editmap: remove dependency on num_trap_ids
Merge remote-tracking branch 'iane/json-traps' into traptrap

Conflicts:
	src/trapdef.cpp
Merge pull request #5 from atomicdryad/pr_json-traps

nuke enums, implement string id methods and automatic backwards compatibility.