When the guard band is enabled, the effective rendering area is
increased by a certain amount (currently 16 pixels on each side) so
that screen-space effects (e.g. SSAO, SSR, DoF) behave better around
the edges of the screen. Of course, this comes at a performance and
memory cost.
Currently the guard band is not configurable other than being optional.
Added c++, java and js bindings.