Implementation of source maps, revision 3, proposed by Google
(https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit)
and Mozilla (https://wiki.mozilla.org/DevTools/Features/SourceMap).

Homepage:
http://hackage.haskell.org/package/sourcemap
