[Bf-python] envalope assignment

[Campbell Barton]

envelope_assignment.py scrpt needs updating
I cant find Jonas Petersen's email, It would be nice to have the scripts 
mostly working for 2.43

the problems at the moment are;
* uses all scene objetcs
* wont work if applySizeRot isnt applied
* method for vertex inside detection looks like it only works  for 
convex shapes, Iv written a functon we could replace this with in 
BPyMesh which can to a test if a points insude a mesh using ray 
intersections.

Id liek to update the script and move over to the Mesh API if Jonas 
Petersen cant.

- Cam