Unify Elisp boilerplate headers

This makes the Elisp headers conform to the conventions described in

 http://www.gnu.org/software/emacs/manual/html_node/elisp/Library-Headers.html

The obsolete `haskell-string.el` has been left out, as it's going to
be removed soon (see d6b83169 for more details)
Remove trailing whitespaces
Replace literal TAB by escaped `\t` in regexp
Untabify Elisp source files

Care has been taken to avoid replacing TABs by spaces in regexps
(such as in 05fe83b).