[EXPERIMENTAL] Add ray tracing for maps

Map tracing
Merge branch 'master' of https://github.com/morphan1/denizen
Improve Rotation.mapTrace

Semi-accurately return the location on the map targetted
Improve entity.map_trace

Actually return an accurate location on the map.
Final code cleaning

Yay for clean code
add location.precise_cursor_on

Note: use with eye_location of entities