UI Improvements

[xanthopoulakis]

As indicated by Marcin

1. Can CN axes always begin at 0 and can we have ticks / horizontal lines only at integers
2. Can we sync all CN axes in the locus plot / pan genome viewer track stack to each other , meaning make all the x axis limits the same
3. zoom function in PP plot is great, but can the zoom be only along horizontal axes? currently also zooms vertically
4. +/- can adjust y axis max to the height of the tallest peak in the current x limits; the issue is that it currently it zooms to the vertical middle of the plot