Language names (rebased off master)

"Arc"
"Clojure"
"Emacs Lisp"
"HTML"
"Haskell"
"JavaScript"
"LaTeX"
"Lisp"
"Perl"
"Python"
"Ruby"
"Scheme"

Two section title changes (in a separate commit), both LaTeX, both in dsl.rmd
A check shows that there don't seem to be any links to them.