Automatic material naming, automatic UV maps, existing CryExportNode support.

Materials will be renamed based on their CryExportNode. Tested with several dozens meshes in different ExportNodes as well as without groups.

I've inserted the utility methods locally since utils contains only very generic methods - however this bloats __init__ even more.
As PEP-8 says: use 2 lines to separate top level class and functions:
http://legacy.python.org/dev/peps/pep-0008/#blank-lines