Stop comparing strings with "is"
Accept lists in place of sequences.
Consolidate child step logic

Adding event listeners.
Checking that child steps are all instances of BaseStep.
Allowing all iterables in place of sequences.
Improvements to sequence controls

Added docstrings.
Added max/min to Bind.
Bind only calls set if necessary.
Remove default max/min from PID.
Listen to events on StateMonitor trigger_step / reset_step.
(Renamed step to trigger_step).
Added StateMonitor.cancel_on_trigger option.
Added test examples for Bind and StateMonitor.