Glitch Controller Minor Bugs

[alex-dewar]

From Discord:

a minor documentation bug to report.
GlitchController.glitch_plot() docstring states: "x_bound (list or None): Boundarys for x-axis in plot"
apart from an obvious typo, it's worth noting a list won't actually be accepted -- only a 2-tuple of (min, max).
same for y_bound.
another funny bug is, calling GlitchController.set_step() explodes in your face if you didn't call GlitchController.set_global_step() even though there is no obvious need to call it. but it's the only place that assigns self._num_steps used by set_step().