Blender Git Loki

Introduce functions/options to indicate the type of render

We should be able to differentiate between OpenGL render (viewport
render), offline render (F12), and view render (viewport draw).

This allows for us preventing offline render to skip mode drawings, grid, ...
Even OpenGL render can benefit from this forcing a higher quality
anti-alias and sampling than the viewport drawing.

I'm not sure if it's clever to keep the memset(0x00) outside the render
loop function as it is in this patch. An alternative is to just pass the
render "type" as a flag to the render function, and set DST.options
inside it. (I may change this tomorrow, I will wait to hear from
Campbell on that).