Clip indicator on multiwiggle tracks should be colour configurable

[carolinebridge]

The clip indicator on multiwiggle tracks is currently strictly red in colour, however this makes it imperceptible if the track is coloured red as well.

We should provide an option in the colour configuration options to colour this indicator differently, and further indicate that there is data that is off the current scale if the user performs an action that causes this to happen.

If the clip indicator is currently active, we should note this beside the option to change its colour in the configuration options.