graphics/nxbe/nxbe_bitmap.c: Fix another coordinate system problem.
graphics/: Review use of device coordinate system with window frambebuffer and make fixes accordingly.
graphics/nxbe/nxbe_fill.c: Fix a coordinate system bug. Was trying to update the window fraembuffer using the device coordinate system. Need to use the relative coordinate system.
graphics/: Use DEBUGASSERT instead of return an error since the is no user to handle the errors within the NX server. Use CONFIG_DEBUG_GRAPHICS instead of CONFIG_DEBUG_FEATURES in most cases.
graphics/: Nothing under graphics/ should set the errno.
