Fix regex for ignoring multi-line comments.

[sagev9000]

.* doesn't pick up newlines, so multi-line comments were not being correctly dropped from the word count.
[\s\S] is a simple workaround, though any of [\w\W], [\d\D], or (.|\s) should also work.

[TheJackiMonster]

You are right. But I think we should use the re.DOTALL or re.S flag instead since it's more legible. See here and in the docs.