Hide cue list indicator on magic sheets

Now that you can target magic sheet objects at pending/active cues on specific lists, there is always a number indicating the cue list visible. On theatre type shows with only one cue list, this can be confusing and distracting when displaying the pending/active cues for the stage manager. An option to disable it could take the form of a checkbox or the prefix could simply not appear for CL 1, just like how the active cue is displayed on the command line.