This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
If the post ids keep loading, we might end up in a situations where
we're always loading the same post ids over and over again without
indexing anything new.
Follow up to daeda80ada.
Also
- Significantly improved search ranking, title is treated most strongly
- Adds tag names to the index
- Run search re-indexer more aggressively
- Re-index topic and all posts on category change