complete places and lucidity columns down to #500

I don't intend to export until the middle columns are filled, as in
its present form the app will read the file as corrupt.
recall column

I kind of skimmed through, so there may be a few imperfect
classifications. But as they say, done is better than perfect.
R will no longer crash if there's no data.

(As in, Python will catch the problem before it sends an empty set to
R.)

Also update the todo list and add a comment about the source of
clearscreen().
display number of occurrences of each place/theme

Was not too difficult, but took unexpectedly long because the
whole function had to be converted to use two dicts where it
previously only needed one list.
themes column

Four down, two to go! Too bad I'm on the last day I can work on
this project...
display relative frequency next to places/themes filter list