Update to 1.12.1

changelog:
pandoc (1.12.1)

  * `Text.Pandoc.Definition`:  Changed default JSON serialization format.
    Instead of `{"Str": "foo"}`, for example, we now have `{"t": "Str",
    "c": "foo"}`.  This new format is easier to work with outside of Haskell.
    Incidentally, "t" stands for "tag", "c" for "contents".

  * MediaWiki reader: Trim contents of `<math>` tags, to avoid problems
    when converting to markdown (#1027).

  * LaTeX reader:

    + Ensure that preamble doesn't contribute to the text of
      the document.
    + Fixed character escaping in \url{}.  Previously `\~` wasn't handled
      properly, among others.
    + Parse `{groups}` as `Span`.  This is needed for accurate conversion of
      bibtex titles, since we need to know what was protected from
      titlecase conversions.

  * LaTeX writer:

    + Specially escape non-ascii characters in labels.
      Otherwise we can get compile errors and other bugs when
      compiled with pdflatex (#1007).  Thanks to begemotv2718 for the fix.
    + Add link anchors for code blocks with identifiers (#1025).

  * Throughout the code, use `isURI` instead of `isAbsoluteURI`.
    It allows fragments identifiers.

  * Slide formats:

    + A Div element with class "notes" is treated as speaker
      notes.  Currently beamer goes to `\note{}`, revealjs to
      `<aside class="notes">`, and the notes are simply suppressed in
      other formats  (#925).
    + Fixed `. . .` (pause) on HTML slide formats.  Closes #1029.
      The old version caused a pause to be inserted before the first
      material on a slide. This has been fixed.
    + Removed data files for s5, slideous, slidy.
      Users of s5 and slideous will have to download the needed
      files, as has been documented for some time in the README.
      By default, slidy code will be sought on the web, as before.

  * HTML writer: Insert command to typeset mathjax only in slideous output
    (#966, #1012).

  * RST writer:  Skip spaces after display math.  Otherwise we get indentation
    problems, and part of the next paragraph may be rendered as part of the
    math.

  * OpenDocument writer:  Fix formatting of strikeout code (#995),
    thanks to wilx.  don't use `font-face-decls` variable.

  * Fixed test suite so it works with cabal sandboxes.