Integerate gcontext_t into setup_opengles_demo.c
Implement pixel_framebuffer_demo

The pixel_framebuffer demo draws
some lines onto a pixel buffer or framebuffer object
and measures how many pixels are drawn.

This is useful if the OpenGL api is used as
2D drawing api. As a 2D api the framework must
ensure that the number and location of the drawn
pixels are exactly what was intended.
Add glapi.h and gles2api.h header in graphic/

Inlucde one of those headers if you want to
draw with OpenGL or OpenGL ES v2.