comment to demo vstack_params_where_state
Added unique values and compress_iter_repr as two utilities for counting repeating value within an array
allow no slice to be passed in to find_toc_tod
Step values (for flaps etc) - bulk of complicated logic re-written to simplify and make more robust against parameters which don't quite reach the desired flap setting or go beyond it a bit. Before it was skipping changes or jumping twice the transition, especially on Flap Lever.
Test cases all checked with graphs and updated to reflect desired behaviour.

Index at value or level off updated to support absolute thresholds.
Flap algorithm except "finally" clause removed.
Flaperon test case updated to reflect move to move_start transitions
derive_parameters docstring comment updated
Nodes now have a "node_type_abbr" attribute for a shorthand node name
flap transition live test data file added
Moved Flaperon to multistate parameters
Flap multistate tests updated to reflect improvements to algorithm.
removed flaperon from derived test
Moved Slat to multistate parameters and created test cases
removed null Slat test case from derived params
Control Wheel test cases improved
Note that get_operational_combinations does not yet support passing the series and family arguments to can_operate
resolved conflict