Make local links work

This adds anchors for all headers so local (in-page) links work (mPDF
doesn't seem to use ids as anchors).
Merge pull request #50 from michitux/locallink

Make local links work
New replacement pattern to pull metadata values in from the Data plugin.  Patterns are of the form: @DATA:column@
Merge branch 'data-replacements' into samwilson

Conflicts:
	action.php