Add a button to toggle between normal and "diplomacy" colors.
Reviewed by: elexis
Comments by: leper, ffffffff, Stan
Fixes: #4747
This was SVN commit r21107.
This also allows non-selectable entities like building previews to cast
range visualizations.
Patch By: Sandarac
Differential Revision: https://code.wildfiregames.com/D555
Refs #3915, #4349, ee5bb1fd61 / D238.
Comments By: Vladislav
This was SVN commit r20622.