Modified the genTestSquare() function so that now the user can specify the location and size of the generated square
minor changes
made it so that RenderableObjects that are not visible will not render
made the uniform update functions non-virtual; added a uniform update function for Object.light_enabled (from the fragment shader)
made it so that RenderableObjects that are not light-enabled will not have lighting calculations applied
Merge branch 'master' of https://github.com/sksharan/OpenGLTest