Reworks tag autocomplete to work the same way for all users. Previously
autocomplete for Builders worked differently than autocomplete for
regular users.
This is how it works now:
* If the search starts with a slash (/), then do a tag abbreviation
match. For example, `/evth` matches eyebrows_visible_through_hair.
* Otherwise if the search contains a wildcard (*), then just do a simple
wildcard search.
* Otherwise do a tag prefix match against tags and aliases. For example,
`black` matches all tags or aliases beginning with `black`.
* If the tag prefix match returns no results, then do a autocorrect match.
The differences for regular users:
* You can abbreviate tags with a slash (/).
The differences for Builders:
* Now tag abbreviations have to start with a slash (/).
* Autocorrect isn't performed unless a regular search returns no results.
* Results are always sorted by tag count. Before different types of
results (regular tag matches, alias matches, abbreviation matches,
and autocorrect matches) were all mixed together based on a tag
weighting scheme.