add TaskQueue interface to Map

- change AsyncTask to be able to post on main-thread
- rename Task.run() -> go()
API: make Rule members public
API: remove setBackgroundMap, add setBaseMap(TileLayer)
API: allow changing number of TileLoader threads
use inverted MeshLayer debug colors
dbg: VectorTileLayer
no need to pre-calc BoundingBox hashcode
s3db: disable postprocess mode

- seems old mali having issues with dependent texture reads..
- add bypass shader for testing
s3db: more material colors