Word-O: New keys & fixes

Another update, this one is pretty major:

Cursor keyboard input added by popular request. This replaces the the old input and reuses the letter status display as a keyboard. Up/Down/Left/Right moves the cursor, A button enters the letter, B erases a letter. The word is automatically entered when the last letter is.

Word checking rewritten: it should now behave exactly the same way Wordle does in this particular corner case.

Also, less exciting: added more words to the dictionary and fixed some small bugs!