-Last (hopefully) few fixes to have all csg calculations/ methods work in web workers
* fixed CAG (2d csg base) clone, to work within weborkers as well
* cleaned up quickhull2d / csg extras file to work properly in workers as well
* tested (manuall) with extrusions, clones, 2d unions etc: it seems ok , will add some unit tests to be sure
* Added a bit more detail about the possible errors generated in web workers (line number, trace etc)