Merge branch 'uvcdat-291-vcs-animation-gui' into uvcdat-master
Move towards the documented Pyton API.  In particular, get from the Diagnostics
 package: 'Types' list, seasons, plot sets list, variables list.
use new API for constructing a obs menu - works only if there is more
than one choice
New obs menu setup should work if there be one observation specified or none
 (not tested)
Fixed #312
Merge branch 'uvcdat-bug312-add_anim_ext' into uvcdat-next
Per Ben's suggestion making sure we check for .mp4 not just mp4 at the end of the file
Merge branch 'uvcdat-bug312-add_anim_ext' into uvcdat-next