Cloud variable changes from Yuying Zhang.
Incidentally, there is a minor change and some temporary debugging prints in plot set 5.
Fix typo in MISR pressure level axis name.
In stdvar2var, treat "no inputs" the same as "not enough inputs".
And I deleted some debugging code.
Replace tests like axis.id=='lon' with axis.isLongitude().
More cloud variables from Yuying Zhang.
Explicitly import derivations.  I don't need it, but others might.
Comment-out some cloud variables without an obs set in their names.  After getting Yuying's opinion
I will either delete them entirely, or else update them to use reduce_height_thickness instead of
reduce_prs_tau.
Insert select_region and interpret_region functions where appropriate in other reduction.py functions
Add default arguments to reduce_time_space_seasonal_regional
Refactor seasonal climatology functions -- try to push all special cases into one function.
A number of small syntax bug fixes and small code cleanups.
Make metadiags.py executable.
bug fixes -- variable names in reductions.py
Bug fix: reduce2latlon_seasonal expects region argument
Fix bugs in calls to calculate_seasonal_climatology (reductions.py)
Refactor some code with generic functions and add delete_singleton_axis to select_lev function.
Add region argument into plot set 3, including function reduce2lat_seasonal.

Conflicts:
	src/python/computation/reductions.py
Add region attribute to reduced variables in plot sets 3 and 5
Force use of local diags.py on rhea for testing (sburrows).

Conflicts:
	src/python/frontend/metadiags.py
Comment out import git statements for testing
Add Southern Ocean and testing sets

Conflicts:
	src/python/frontend/metadiags.py