Squashed commit of the following:
Clean-up some include path problems introduced with the previous set of changes.
app/include/graphics, apps/NxWidgets/UnitTests: Update include paths for file in new location.
apps/NxWidgets/nxwidgets and nxwm: Update include paths for file in new location.
apps/graphics/NxWidgets: Move nxwidgets and nxwm include/ directories to apps/include/graphics