Disable some actions when the program is started.

With this change these actions:
- pause
- propose_draw
- adjourn
- resign
- abort
will be disabled when the program starts, however a subset of them will be
activated when the game starts, depending on what the protocols support.

Whithout this change I could crash the program doing this:
1. Start the program.
2. Click "Cancel" on the new game dialog.
3. Click the button for any action listed above.