The original obj importer was ok but it gradually got slower
as it had to support quirks of rare files.
This importer supports these quirks without bad workarounds and ~250 less lines.
* Moved from NMesh to Mesh
* Import smooth groups as hard edges
* Import Lines from sketchup (Thanks Wavk)
* Uses less memory
* faster (On a 70meg poser test model, benchmarked from 130sec to 41.2sec)
Not yet supported from the old importer-
* Scaling down to a bounding area
* Importing multiple obj's at once
* Using existing materials in the .blend
* Importing as a group instance.
