Expand post categorization, refactored internally for now, in order to:
- Allow more complex / standard language tagging that isn't easily expressed in hashtags
- Make it easier to consistently categorize posts
- Support T495: List all tags on a blog
Some discussion of this on the forum.
Whenever a user publishes, updates, or deletes a post, update a table of data with all used tags.
TODO: revisit this schema; not sure what's most fitting.