Merge pull request #39 from SirSlaxalot/master

fixed error return value
Fix for issue #40: Added support to render using premultiplied alpha

- added support to take screen shots
- added support to render to frame buffer using premultiplied alpha
- fixed spelling NVGaling -> NVGalign
Merged latest changes from fontstash

- merged font stash optional FreeType support
Improved miter and bevel line joins
Variable initialization, unused var removal, and casts.

Removed some unused variables to silence compiler warnings, initialized
variables to 0, added varialbe casts to silence additional compiler
warnings.
Fixes for AA on retina, a bit finer tessellation

- changed tessellation threshold from 0.3 to 0.25
- fixed scissor AA on retina
- fixed stroke AA on retina
Merge pull request #50 from devnought/dev

Variable initialization, unused var removal, and casts.