- 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
write_plot_data() writes NetCDF files (rather than crash)
This is a bit better for the "standard" batch.py script, as it writes NetCDF files.
- new class uvc_composite_plotspec, will replace a list of uvc_plotspec objects for output.
This lets us assign title to a composite plot and provides a place to put:
- new method write_plot_data() of class uvc_composite_plotspec.  For a composite plot, writes
an xml file describing its pieces (simple plots), and calls their methods to write them out.
- The class uvc_plotspec remains for backwards compatibility, but otherwise has been replaced
by uvc_simple_plotspec, which defines a single simple plot for output purposes.
Print a composite plot as an xml file (plus NetCDF files for the simple plots it contains),
using a new write_plot_data method.  There is no more list of simple plots, no more loop over
these plots printing NetCDF files one-by-one.
minor fix which I had planned to include in the previous commit
- plot_these and presentation attributes so the NetCDF file will be a self-contained plot description
- work-in-progress, not finished, on a finalize() method of uvc_simple_plotspec.  This will be sometimes needed
for computing range information about a plot.
- some minor bug fixes and workarounds, e.g. for a file name too long.
- finished first cut at finalize method for plot scaling; at least it works
- tentative new code to write data to file out of plotdata_run; not tested
call finalize for some more plot sets
Merge branch 'master' into elo

Conflicts:
	src/python/frontend/uvcdat.py