Indexed face set import

- Imports the geometry, using the points and the coordIndex. Know issue: you *MUST* remove texCoordIndex if present, since that matches as well and distorts it. I am still working on a more reliable tree, which would eventually be validated. Also: transparency in an IndexedFaceSet material might need to be removed or commented out.
- The tree nodes now also have a comment and a nodeType property.
- Comments can now be anywhere in the VRML, no longer need to start at the first char of a line
- Doublesided material on all material to support indexed face set with arbitrary mixed normals, as those used to be supported in VRML when solid was set to false. This must later be only applied if indeed solid equals false, once I have added support for that.