Fix 'Ext_lists_without_preceding_blankline' bug.

  * Fixes #1636.
  * Adds a test.
DokuWiki writer:  Better handling of block quotes.

This change ensures that multiple paragraph blockquotes are
rendered using native `>` rather than as HTML.

Closes #1738.
Org reader: absolute, relative paths in links

The org reader was to restrictive when parsing links, some relative
links and links to files given as absolute paths were not recognized
correctly.  The org reader's link parsing function was amended to handle
such cases properly.

This fixes #1741
Org reader: allow empty links for gitit interop

While empty links are not allowed in Emacs org-mode,  Pandoc org-mode
should support them: gitit relies on empty links as they are used to
create wiki links.

Fixes jgm/gitit#471
Merge pull request #1742 from tarleb/org-fix-links

Org fix links
Merge pull request #1645 from neongreen/issue1636

Fix 'Ext_lists_without_preceding_blankline' bug.
Account for external link URLs with anchors

Previously, if a URL had an anchor, such as

    http://johnmacfarlane.net/pandoc/README.html#synopsis

the reader would incorrectly identify it as an internal link
and return "#synopsis" for the link in output.
Add tests for external links with anchors
Fixed bug in org with bulleted lists:

   - a
   - b
   * c

was being parsed as a list, even though an unindented `*`
should make a heading.  See
<http://orgmode.org/manual/Plain-lists.html#fn-1>.
Changed mime type for otf to application/vnd.ms-opentype.

Closes #1761.  This is needed for epub3 validation.
See http://www.idpf.org/epub/20/spec/OPF_2.0.1_draft.htm#Section2.3.1
Removed extra `</body>` tag from `tests/html-reader.html`.
Make `embed` tag either block or inline.

Closes #1756.
epub, epub3 templates: Added id="cover" to body of titlepage.

This aids styling, making it possible for example to set 0 margins
on the title page.  Closes jgm/pandoc#1758.
Removed extra body tag from epub3 template.

This fixes a bug introduced by the previous fix.
Use regular page template for nav.xhtml.

This includes the HTML doctype.

Closes #1759.
export more Html functions and use StateT monad transformer instead of State in order to implement Toc extending to subpage in gitit2