redraw, add preview of tile painting when tile is hovered
Suggestion for a small improvement in the Redraw and Redraw Symmetrical activities. Now, the mouse hovered tile will display the selected colour, to indicates what change will a mouse click do.
At the moment, I am not a big fan of the resulting colours of `Qt.lighter`. I might improve this MR by using a new table of manually chosen colours for this use.
(I really have to find a good way to capture/present my changes :'))