Fix interaction between kak/replace-char, kak/select-to-char, and multiple cursors

[Joseph Morag]

See the README. These commands prompt for input once per cursor instead of just once.

[Andrew Scott]

The interactive forms should apparantly use read-char to work with multiple-cursors:

(interactive (list (prefix-numeric-value current-prefix-arg)
                   (read-char "Zap to char: " t)))

https://emacs.stackexchange.com/questions/18716/why-does-multiple-cursors-use-the-same-char-for-all-cursors-with-zap-to-char-but