Added convenience function to operators, 'as_keywords()', so operator settings can be passed directly to a function as keyword arguments.
The problem in this case was that dictionary access to operator properties was not returning rna-property defaults, so as_keywords() ensures all defaults are set.
- made operator dir's into python packages
- lazy loading of module which do the actual import and export (faster blender load times)
- general maintanance and small fixes.
- bugfix for exporting x3d materials
- leak fix for exporting 3ds