Score with scrabble bonus
Show blanks as lowercase
Accept letter on edge
If tile on the board is blank do not count it
again accept letter on edge
Letter in lowercase if blank on solution
Better place to assert for edge on add_word
look if letter is blank on new_board not only on word_blank_indices
Update board.py

assert for edge < instead of <=
Merge pull request #2 from flibustenet/master

Merge changes by flibustenet (show blanks in lower case; allow words to end on last column/row; add scrabble bonus).