Typo in README and cleaner code  in glfons__renderUpdate

README.md: Kinda obvious. There is no glstRGBA function.

glfons__renderUpdate:
I personally run into this. My program updates textures in each draw, and all the textures became garbage after I started using Font Stash. Took a bit of debugging to hunt down the reason why.
I think it's nicer to save and restore these settings, since they are not used that often.