Merge pull request #38 from andrewcorrigan/master

reduces warnings
Improve stroke rendering

- added better logic for inner bevels
- tweaks to reduce overdraw at edges
- fixed convex shape logic
fixed error return value
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.
Update README.md
Updated fontstash
Added quick hints on how to debug rendering issues
Small addition to debug hints
Moved to floating point color via NVGcolor structure.
Currently working with gl3buf backend.
Converted gl2 path.
Converted gl3 unbuffered version.
Warning/Error fix: added int return type to nvgIsBlack
Converted spaces to tabs.
Added nvgRGBf and nvgRGBAf constructor functions.