2. add more gnuchess switches
3. human-human playing
4. xor piece while user moves it
5. gray background for dark squares in 1-bit mode
6. alternate promotion code
7. positions assume that White is on move
8. slow down TwoMachines mode
9. manual position setup
10. add time odds to record-file
12. analog clocks, scoresheet text widget, jail
13. -iconic doesn't work correctly
14. indicator for force moves mode
