Reduced jar frequency.
Prevent divide by zero in scent display code.
Make scent normalization much slower.
little optimization.

I noticed a bunch of wolves checking for lit torches too often.
removed bottleneck in saving&loading of mapbuffers

list.size is O(n) with some stl implementations, and it was
sizing the submap list every time a submap was loaded or saved.

Conflicts:
	mapbuffer.cpp
Slightly reduce calls to map::i_at() by holding a local reference to it.
Const all the things in map.cpp and map.h.
Reduce calls to map::field_at() slightly by holding onto a reference to the field.
Continue to constitutionialize map.cpp and map.h.
fixed toolless constructions
Merge pull request #24 from wito/master

Some new vehicle parts
Merge pull request #25 from wito/loadable-skills
Merge pull request #26 from zpmorgan/master

misc fixes