Trick debug_pause debug_counter no longer works

[miltondean]

In the Trick 13 instruments.debug_pause.debug_counter works correctly. When set to a non-zero value, the simulation should enter Step mode. Every time the Step is selected from the Sim Control panel, the debug_counter decrements and when it hits 0, the Step mode ends and the the simulation continues as normal.
In Trick 17, instruments.debug_pause.debug_counter was updated to be trick_instruments.debug_pause.debug_counter, and it appears an error was introduced into this processing so that it no longer works.