Feature request: Make material import optional

[caniko]

As mentioned in #53, material files may not have the same name. Moreover, in my case, I don't have any .mtl files paired to my obj. files. I just want to use the parser to import vertexes, normals, and faces to my script.

Solution:
Make a keyword argument that takes file path for .mtl files. Also add a secondary keyword argument that is a bool for skipping material import. Use a default material (grey?) for rendering if material skip is set to True.

[einarf]

Do you have a real life example of materials names and usemtl statements?

[einarf]

If you just want to use the parser to import vertexes, normals, and faces you can use the create_materials=True parameter so everything will use a default materal instead? (assuming you have no mtl files)

[caniko]

Do you have a real life example of materials names and usemtl statements?

No, but it seems like a kwarg worth having for the comfort of the enduser.