Updated changelog.
Further changelog formatting cleanup.
Fixed a couple test files in cabal file.
benchmark:  Remove haddock (no writer to create reader input).
`--bibliography` again implies `-F pandoc-citeproc`.

But only if pandoc-citeproc isn't already specified as a filter.
Mediawiki: Parse an image + caption in a para by itself as a figure.
Updated changelog.
Changed pandocfilters repository URL.
Updated README on pandocfilters python module.
HTML writer:  Ensure proper escaping in header metadata.
Markdown writer: Print references if output is 'plain'.
README: Added link to lua.