NxWidgets improvements
* NxWidgets: fix garbage returned when CCycleButton::getValue() is called after removeAllOptions().
It's a bit questionable whether returning 0 here is reasonable or
if it would be better to assert(). But either is better than reading
into random memory and returning a garbage value.
* NXWidgets CScrollingPanel: Don't draw outside the widget area.
The port->move() function doesn't support clipping the
copied area to the client area, so we have to manually
calculate the part that can be moved without going outside
the widget.
* CNxString: Add string + operator and ::format() function
* CNumericEdit: Add option to include unit name after the value
* NxWidgets: CNxWidget: Make useWidgetStyle() public
Makes it easier to update styles when multiple controls are nested.
* NxWidgets: Add CLabelGrid control for displaying text in grid format.
Approved-by: GregoryN <gnutt@nuttx.org>
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
