- support ranges - minima and maxima of variable values and axes in a plot; and synchronizing ranges
among plots.  This still has to be tied in to the GUI.
- first cut at sample range interface, originally from Charles
include aux options (variable levels) in generating plots
In aminusb_2ax, allow a third axis if it's trivial and can be ignored; for now, this works only if
this trivial axis is axes[0].
- delete some obsolete code
- compute and synchronize ranges
- In finding level sets, allow obs to use pressure levels, or hybrid levels like the model.
define an _all_variables() method for plot set 2
Reverse arrays for observed NCEP heat transport, so they will be more compatible with model data for plots.
Logically, this job should be done by the graphics package, but it doesn't look like it will ever get implemented there.
Merge branch 'master' of github.com:UV-CDAT/uvcmetrics