Constraints action in word edit

[philhanna]

Requirements

When editing a word, have a button that finds the constraints imposed by the crossing words, building a regular expression that will satisfy them all:

• For each letter of the word:
  • Find the word that crosses this letter
  • If the corresponding letter in the crossing word is not blank, put it in the regexp.
  • If the corresponding letter is blank:
    • Lookup all possible words that match the current pattern of the crossing word
    • Collect the possible letters at the crossing cell
    • Put a [...] in the regexp with the possible letters.
• Put the completed regexp into the word input field so that the suggest button can use it.

I already use this logic manually, but it takes long time. This will speed it up considerably.