plot_plane_using_scans now produces size-correct figure which when saved with
the correct DPI is 1-1 comparable with microscope images
savefig in utils now accepts a pixelsize_um keyword argument
Adds with_tics and scale keyword arguments to plot2d, which allows plotting of
aspect-correct images
Updates truncation algorithm in plot.py, which now also complains if you give
it no files to plot
Adds scale parameter to plot_plane_using_scans in plot2d instead of using an
arbitary one and returning it.
stats.py now outputs stats for all columns
Removes imagej_compat from plot_yz_plane_using_scans  because
plot_plane_using_scans now handles it
Removes default value of 3.2 for pixelsize_um in savefig