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.
graphics/nxterm: Needs to clear display initially. Otherwise, garbage from previous display may still be present from preceding NxWM window.
graphics/nxterm: Back out most of the preceding NxTerm changes related to window size. apps/examples/nxterm passed the complete NxTK window size. Those changes were needed to make aps/examples/nxterm work. But NxWM passes the the size of the NxTK main sub-window. So I needed to back out the changes and then change the applications so that they passed the same value (the size of the NxTK sub-window).