change test for no-mask to one which works when there is a mask
new method so outside objects don't have to access _inputs directly.
New special-case in __getitem__ to serve code which mistakenly does foo['coords'] when it should be
calling foo.coords().
Fix two names: plotall_id for plot sets 1 and 2, so that it will differ from plot1_id even when
there is only one filetable.  Names and ids don't work unless they're unique!  This probably is
needed for other plot sets as well.
- added lots of new cloud variables
- better error handling in stdvar2var
Minor improvements in error handling, line breaks, etc.
added some land diagnostics examples