VCO.Timeline.add(data) doesn't draw time axis correctly

In exploring the process of slide and marker instantiation (to understand what it would take to address #197) I manually tried adding a slide by copying the JSON data for a single event and calling timeline.add(data). It seemed to create the slide and marker correctly and position them correctly, but the axis ended up all bunched together.

Zooming in and out on the timenav eventually reset everything, so probably there just needs to be a call to reset the axis somewhere in https://github.com/NUKnightLab/TimelineJS3/blob/6da33b0f567502b0e4465428aac83dcb191abfe9/source/js/VCO.Timeline.js#L301-L314

Since direct manipulation of the timeline instance like this isn't a high priority feature, we might put this in 'future', but I also think that sorting this out might tighten up the code a lot, so part of me wants to set it in 'cutover'

Start in source/js/VCO.Timeline.js at lines 301-314 and reproduce the issue by copying one event's JSON and calling timeline.add(data). Compare the axis before and after zooming in and out to identify the missing reset step. Done means the time axis is laid out correctly immediately after adding the slide and marker, without requiring zoom interaction.