Update render script to use clear color from config. (#45)

Squash-merge PR: Don't use extra vectors in transforms. Add arg to re…

…turn raw coords.

Update render script

- Remove deprecated `render.draw_debug2d()`
- Set stencil mask.
- Fix tabs.
- Rearrange things a bit and remove some unnecessar state changes.

Based on the latest built-in render script and the model rendering
script in the render manual.

Update v1.0 release tag