Small changes for compiling with MSVC 2013.
Remove #ifdef guards.
Merge ESM::Cell fields by subrecord

Fixes an issue with the Morrowind Patched mod where cell ambient values would become black due to the new cell records not including an AMBI subrecord.

Also fixes a bug where mLeasedRefs was incorrectly cleared when overwriting a cell (*oldcell = *cell;)
Change openmw.log to boost ofstream to fix unicode path on windows (see https://github.com/OpenMW/openmw/pull/108)
Don't play the same music track twice in a row (Fixes #746)
Store keybindings as keycode, not keyname. Also use SDL_GetKeyName instead of a manually created map. Fixes #1202

Note: breaks compatibility with input.xml, so the filename was changed.
Cell merge fix (reference context position was not saved correctly)
Merge remote-tracking branch 'upstream/master'
For compiling with MSVC 2012
Don't check mInterpolationType each iteration
Merge remote-tracking branch 'cc9cii/master'
Merge remote-tracking branch 'scrawl/master'