Added & linked mention of yak-lang.org.
Researched the title of common language websites: Python Programming Language, Ruby Programming Language, HaskellWiki, CoffeeScript, Erlang Programming Language. Concluded that '<name> Programming Language is the most pervasive'; retitled yak-lang.org
Cleaned up style.css
Linked List::every and List::any.
Documented .union.
Documented .intersection; qualified .union!.
Explained .intersection!
Documented List::reverse!