DemoBitmapPathfinding:
 - back to UInt in RandGenerator (waiting for response on haxe issue #3552)
 - html5 bitmap loading delegated to openfl
 - couple of _assert_ added
Fixed bug causing crash when no tangents were found (Funnel.hx)
Merge pull request #5 from azrafe7/bitmap-pathfinding

Azrafe7 has tidied up my bitmap pathfinding demo to work better... DemoBitmapPathfinding