Tool to toggle element state

[btzy]

This tool should toggle element state immediately, regardless of whether the simulator is running.

Tool should be able to:

• Toggle logic level or logic gate or communicator
• Toggle conductiveness of relay

[xsot]

Since toggling an element's state is probably not a common task, it may be wasteful to assign an entire new tool to it. We can consider shift-clicking with the Interactor instead.