Add FBO handling

Preliminary implementation to add FBO handling to gl_utils.
Ready for code review.
Compilation not checked (I have just adopted the new convention of gl_utils libs)

As I'm using glfw to check the FBO support we have perhaps to delete the following function :
bool GlFrameBufferObject::checkIfHardwareIsCapable()
{
  return glfwExtensionSupported("GL_framebuffer_object")
    || glfwExtensionSupported("GL_ARB_framebuffer_object")
    || glfwExtensionSupported("GL_EXT_framebuffer_object");
}