Add support for punctuation

[gabevenberg]

Monkeytyper has a mode that adds randomized punctuation to words in a test, such as a period/comma/colon/semicolon at the end of a word (periods making the next word capitalized), a dash between words, or surrounding the word with a delimiter, such as parentheses or quotes.

Would be nice to emulate this, to simulate english prose with all its punctuation without resorting to full book exerpts.

[gabevenberg]

Actually, looking through the codebase, I think this might be something I can pound out over the next while. Ill start working on a PR.