[Papervision3D] New package structure

[Paulius Uza]

Hello,

Please consider the following changes to Papervision 3d package:
- Papervision 3d should assume that we have loaded our assets prior to 
calling functions that need them. In other words - I suggest removing 
the integrated file loading mechanism from inside several functions.
- Create a separate and independent Papervision 3d object for loading 
assets.

A little explanation: people may want to use different file loading 
techniques or would want to fully control the loading process.

Regards,
Paulius Uza