Option to plot light curve using epoch number

[ajstewart]

When looking at data that spans a lot of time, e.g. years, plotting the light curve of the running catalogue against date is sometimes not the most useful as you have to zoom in and out to see specific points, plus you cannot gain a good sense of the overall picture.

It would be nice if there was a toggle between plotting the actual dates, or plotting the flux values vs just the epoch number. By this I mean if I had three time epochs of 1 January 2011, 2013 and 2015, the flux values would be plotted against numbers 1, 2 and 3 instead of being two years apart.