Write full metadata in MMD style title blocks.
Fixed bug retrieving default template for markdown variants.
Markdown reader: Better error messages for yaml headers.
Markdown writer:  Changed condition for rendering title block.

Previously it was only rendered if title, author, or date set.
Now any metadata field can be set.
Rename `Ext_yaml_title_block` -> `Ext_yaml_metadata_block`.
Document YAML metadata blocks.
`--toc-level` no longer implies `--toc`.

Reason: EPUB users who don't want a visible TOC may still want
to set the TOC level for in the book navigation.
make-windows-installer.bat:  Removed explicit paths for executables.
default.latex: Use tex-ansi mapping for monofont.

This ensures that straight quotes appear as straight, rather than
being treated as curly.  See #889.
LaTeX writer: Don't use ligatures in escaping inline code.
Text.Pandoc.UTF8:  Use strict bytestrings in reading.

The use of lazy bytestrings seemed to cause problems using
pandoc on Windows 7/8 64-bit machines.

Closes #874.
Docx writer: Use w:br with w:type 'textWrapping' for linebreaks.

Previously we used w:cr.

I don't see a difference between these in my version of Word,
but apparently some do.  Closes #873.
Parse LaTeX figure labels if present