Blender Git Loki

So! Finally time to work on finishing render pipeline project.
This commit brings back:

- Field Render
- MBlur Render (old style)
- Border render with or without cropping

Note: Field Render is not supported in Compositor yet. Blurring or filter
will destroy field information.
Both MotionBlur as Field render are done before Compositing happens.

Fixes:

- The "Save Buffers" option only worked on single frame renders, not for
Anim render.
- Found an un-initalized variable in Render initialize... this might have
caused the unknown random crashes with render.

Code restructure:

Cleaned up names and calls throughout the pipeline, more clearly telling
what goes on in functions.
This is visible in the updated first image of the Wiki doc:
http://mediawiki.blender.org/index.php/BlenderDev/RenderPipeline