Split mobility state into external files

Hero has some complex state machine goodness that was bloating his
class, so I separated out the classes into their own files. They're all
forward-declared in Hero.hpp.
Code cleanup, comments, debug #defines

Added HIKARI_DEBUG_HERO_PHYSICS to exclude some debugging counting code.
Fixed README, added MISC for notes
Renamed RetroVector to NESNumber

Also updated affected classes...
Added HIKARI_DEBUG_ENTITIES, updated Entity

Removed extra debugging stuff by putting it behind a preprocessor
directive.
Updated squirrel3 version to latest
Fixing compiler warnings + interface changes

Some assignment operators are not or cannot be auto-generated so I need
to add them.
Added get/setWorld to Entity

Plumbing changes for how entities interact with the world.
Fixed update/pass by value in some classes

Updated the ::update method for various classes to accept `float dt` by
value rather than const-ref.
Whitespace
Added empty CMakeLists.txt
Removed contrib/gme, added gme-nes, added Faction
Merge branch 'master' into cmake
Added MSVC defines to ignore security warnings
Moved jsoncpp to extlibs, building source into engine:
Merge branch 'master' into cmake
Deleted gme from contrib
Merge branch 'master' into cmake
Moved some small libraries to /etxlibs
Added CMakeLists.txt