Merge uniforms into a single uniform array

Add FBO support for GLES

Fix for issue #162

To support FBO for iOS, the current framebuffer and renderbuffer must be restored after calling nvgluCreateFramebuffer(). The framebuffer should also be restored when calling nvgluBindFramebuffer(NULL) as well.

Conflicts:
	src/nanovg_gl.h

- API changed!
- moved image repeat from nvgImagePattern() into image creation
nvgCreateImage*()
- made flip-y and premultiplied common image flags (not just GL)
- removed nvglImageFlags(), flags passed in via
nvglCreateImageFromHandle() flags
- nvgluCreateFramebuffer takes image flags as param

- added NVG_DEBUG which can be used to omit calls to glGetError()
- removed return value for glnvg__checkError
- create flag defines to enum

added new graph style

Fix texture completeness for non-POT textures on GLES2/WebGL

Restore openGL state / unbind buffer

These changes make it possible to integrate nanoVG into other openGL libraries like Cinder and openFrameworks and be able to draw afterwards.

- removed duplicate call to nvgTextMetrics()

- set default lineHeight to 1.0

Set commandx/y before the transform

This prevents commands like `nvgQuadTo` and `nvgArcTo` from double-transforming the previous point when they pass it back to `nvg__appendCommands`.

- added function to allow to combine scissor rects using intersection

- added projects section to read me
- added processing API link (issue #135)

- added typedefs for all structs
- fixed some compiler warnings

only specify precision for fragment shader

- set stb_image flags so that it loads correct data in iPhone

update upstream stb things.

Auto detect and resize text altas texture.

allows for nanovg_gl prototypes to be declared simultaneously

Tweaked premake to remove some windows warnings.

second attempt at avoiding warnings at /W4 on vs2013

use -1 as the 'no scissor' value, rather than 0, so that 0 width still scissors

Memory leak + small fixes