Ignore #comments and empty lines while parsing .obj and .mtl files.

There is no point in creating a StringTokenizer for a comment or an empty line.
I noticed that SketchUp adds lots of comments to its .obj and .mtl files.
This update should slightly speed up parsing by ignoring comments and empty
lines at the very first opportunity.
Merge pull request #312 from ccoffey/master

Ignore #comments and empty lines while parsing .obj and .mtl files.