* Moved code for translating listings language names to
highlighting-kate names and back from LaTeX reader to Highlighting.
* Text.Pandoc.Highlighting no longer exposed (API change)
* Text.Pandoc.Highlighting exports toListingsLang, fromListingsLang
Previously header ids were autogenerated by the writers.
Now they are generated (unless supplied explicitly) in the
markdown parser, if the `header_identifiers` extension is
selected.
In addition, the textile reader now supports id attributes on
headers.
Taking into account new context/latex output, and fixing
some bugs in the test suite Tests.Helpers and Tests.Writers.ConTeXt.
(We had the wrong order of expected/actual in the diff output.)