Highly recommended

Enhancements

@@ -0,0 +1,9 @@
+-*- mode: org -*-
+
+1. [X] Mark suggested words with the "recommended" class when the word forms a valid word both across and down for words that intersect at the current square.
+2. [X] Mark suggested words with the "highly-recommended" class when the word forms a valid word both across and down for *all* words that intersect the word.
+3. [X] Implement an "undo" function that sets the state of the puzzle back to before the last pick of a suggested word.
+4. [X] Show where the symmetric square is in the puzzle. Perhaps bind this to "," which, when pressed, highlights the symmetric square to aid users before they actually black out a square.
+5. [ ] Allow black/unblack square operations to be undone. (Also clear tiles?)
+6. [ ] Support regular expressions in the puzzle. Suggestion: allow digits 0-9 in the puzzle, which refer to one of ten regular expressions. For instance, regex 1 might be any vowel (i.e., /[aeiou]/) and regex 3 might refer to whatever matched in regex 1 (i.e., /\1/). So we could specify something like "B 1 3 K" which would match "book" but not "beak".
+7. [ ] Support a dictionary lookup of a clue on hover.