Alpha test release 4.2.0a56

Fix (again) counter-attack issue.
Stacked Leader piece presents Rally & Unsquare commands
Game setup: deck selection from observer mode & side random draw is available also after deck selection, until a side has been joined.
Unit ordering/moved highlighting, to provide better contrast with all army colours and not over-lay the piece graphics.
Optional flag markers will distinguish Russian and Prussian pieces from French.