-Added Distance based Depth of Field (not object based yet)

-Noticed a bug when parts of an object are flat shaded and other parts smooth shaded, not solved this yet.

Removed some lines for caustics that turned fake caustics off when photons were on, thereby changing the scene data, which is to be avoided. It seems P.O.V.ray takes care of the override all by itself so the lines were useless anyway.  

I had forgotten to change some names I hope it does work  now; This is an adaptation of Povray exporter to render with povray 3.7 
if you want more info, there are pdfs in the zip files here on the tracker: https://projects.blender.org/tracker/index.php?func=detail&aid=22717&group_id=153&atid=468

- mist wasnt updated for rna renaming
- meshes with no faces were failing

These scritps still need changes related to parent classes
- mesh_surface_sketch.py
- render_renderfarmfi.py
- space_view3d_align_tools.py
- object_cloud_gen.py

After discussion with Campbell I've made povray an addon as a package (will remove from bf-blender).
Please roport any glitch or mistake I might have done while porting.