Reorganized the whole pov properties, to place them in PropertyGroups, rather...

Reorganized the whole pov properties, to place them in PropertyGroups, rather than cluttering the Scene/Material/etc. objects’ spaces…
Also added a new file handling the conversion from existing files using the old pov properties (call the ˘povray render: update to script v0.0.9” operator (bpy.ops.scene.pov_update_properties) in the search box of the 3d views to make the conversion).