Rewrote Detailed Block Rendering.

Apologies for the large PR, it kinda spiraled out of control, I originally only intended to make a few minor improvements, but I just couldn't stop until I liked the results.

Using a really long winded cache based system, I replace the render code of detail blocks with one that uses a single lighting calculation and interpolated color/brightness.

I also filtered the rendering to ignore "voxels" that are interior blocks.

Over all the result is vastly improved rendering speed 5-6 detail blocks no longer cause the chunk to lag when re-rendering.

A few notes about quality:
This fixes the breaking animation of detail blocks, and fixed the strange "block like" look that sometimes appears in the brightness, so over all I think the quality is better, the down side is that some sides appear darker then you might expect when they are next to solid blocks.

But a think that the improvement(s) is worth the down side.