add TagTermParseEvent for parsing tags during tagging
make "source[=|:]none" null the source
option for add_post & remove_post to log history
(for use with TagTermParse)
also make navbox show on pool history page
vote[=|:](up|down|remove) metatag
Post Relationship ext
thumbnail border-color for post relationships
also removed build_thumb_html from themes (mostly old versions of the default base function)
check for permissions
make sure source/parent isn't set twice if metatag is used
updated docs with new metatags
Merge pull request #378 from DakuTree/patch

Post Relationships ext + TagTermParseEvent