Add rectangle tool to PCBNew toolbar in favour of Aux Origin.

ADDED new rectangle graphics tool for PCBNew and Footprint Editor.

Also adds rectangle tool to both Footprint Editor and PCBNew Place
menus.

The Aux Origin tool can come back once we have multi-select toobar
buttons.

Also collapses an unnecessary level out of the auxOrigin and gridOrigin
settings.

Fixes https://gitlab.com/kicad/code/kicad/issues/2246

pcbnew/pcbplot.cpp

@@ -341,7 +341,7 @@ void AddGerberX2Header( PLOTTER * aPlotter,
     // Please, if absolute Pcbnew coordinates, one day, are set by user, change the way
     // the key is built to ensure file only using the *same* axis have the same key.
     wxString registration_id = "Original";
-    wxPoint auxOrigin = aBoard->GetAuxOrigin();
+    wxPoint auxOrigin = aBoard->GetDesignSettings().m_AuxOrigin;
 
     if( aBoard->GetPlotOptions().GetUseAuxOrigin() && auxOrigin.x && auxOrigin.y )
         registration_id.Printf( "PX%xPY%x", auxOrigin.x, auxOrigin.y );