Added PixMap::setBuffer function.
Empty texture (render texture) initialization.
Added texture rendering FBO initialization.
Created the renderToTexture and endRenderToTexture functions.
Convert the ColorFormat Enum to the new lua friendly enum.
Added a way to set the viewport and context size with the renderToTexture function.
Updated all the call to the ColorFormat enum.
EAGLView won't call glviewport anymore.
Fixed a bug with context size on iOS.
Added the render to texture related function in swig.
Merge branch 'feature/RenderToTexture' into develop