RB: Add new admin message type for switching trading modes
RB: Add new Administrator command for switching trading modes.
RB: Add new action for handling switch trading mode command.
RB: Add trading mode display and switch trading mode button to admin client.
RB: Implement active, passive, and startup trading modes.
RB: Modify order book access methods to make copies of lists before iterating.
RB: Modify trading simulator to use Simple Distributed Trader by default.