Just don't try to save space by only selecting few attributes. If
anyone is wondering, this is needed because the emoji entity cache
is not really only used for entities, it's accessed again to
generate Emoji tags in ActivityPub/OStatus, so a lot more properties
are used than what is needed in HTML alone...

* Add entity cache

Use a caching layer for mentions and custom emojis that are
dynamically extracted from text.

Reduce duplicate text extractions

* Fix code style issue