Fixed fonsDrawDebug (added missing fons__flush() call at end of function)
Merge pull request #17 from johnbartholomew/fix-debug-draw

Fix fonsDrawDebug
Added error callback

- added error callback on atlas full, scratch mem full, and state stack
under/overflow
- preparing to more debug rendering, added white rect @ 0,0
Added atlas expand and reset functionality

- added function to reset atlas/stash
- added function to expand atlas size
- fixed texture creation bug (used width for height)
Fixed logic bug in atlas full error handling
Changed fonsReset to fonsResetAtlas for constancy