Maths; : MINOR API CHANGE :  DEG2RAD -> _PI_OVER_180 and RAD2DEG -> _180_OVER_PI . This is more explicit as to what the value is, especially since it is useful for more than just deg/rad as a static value. Added documentation to suggest using degrees() and radians() as those are inline i.e don't show up in final code and make the user code clearer as to intent.
Tilemap; TilemapVisual; initial work on #144 and #152, expose options as a property of the visual. needs more maps and test cases in the test