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.
Merge remote-tracking branch 'zpmorgan/master' into for-darklingwolf
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.
Lockpicks now required to silently open doors
Merge branch 'master' of https://github.com/TheDarklingWolf/Cataclysm-DDA
Merge remote-tracking branch 'upstream/master'