- fixed tiny bug : now doubledsided attribute of meshes is set correctly (for canvas/software renderer only)
- fixes #62 :  stl export issue
* turns out there were actually two issues:
 * canonicalized() was not called (or force called) after retesselation , therefore, duplicate, overlapping vertices were not merged
 * the automatic javascript -> coffeescript conversion of some of CSGBase's methods (particularyl FixTJunctions in our case)
 completely botched some for loops (converted them to while loops with never met end conditions): so I changed most of these back into
normal (but coffeescript style) loops , and fixed a few additional bugs that made the exporter go into endless loops
 * all csg base operations (union, subtract, intersect) modified so they invalidate the tesselation and canonicalized state of the object (forcing the merge of redundant vertices,
see above)
- changed reTesselated() and canonicalized() to reTesselate() and canonicalize() (more coherent naming since now these methods change the current object
instead of returning a new one)
- converted a number of loops to list comprehensions in CSG.coffee (potential speedups?)
- fixed the cutByPlane method (moved to new api of object "self modification instead of returning a new one)