Blender Git Loki

Improvements for knife tool execute function (code was a bit sloppy & could leak memory).

- vertex to screenspace projections were not checking for failure to project (vertex behind the view for eg).
- vertex screenspace 2d vectors were each malloc'd and added to own ghash, then fetched for each edge.
now just store a vertex aligned array and do index lookups.
- projections were done in global space, now do them in object space (avoids a matrix multiply).
- error cases were commented out and would fail silently, now report them to the operator.
- remove MAX_CUTS hard coded limit, dynamically allocate the mouse path.
- add missing free calls in error cases.