I've reworked the SELECT completion patch to use the VersionedQuery
infrastructure.
I've also made it a schema query (for the functions), with an addon
for the attributes. This provides schema-aware completion.
Previously, addons to schema queries were appended verbatim; I've
changed this to use the same interpolation just as in the simple_query
case, so that the attributes can be filtered in the query. Otherwise,
relevant items can be omitted when they don't make it into the first
1000 rows in the query result, even when only a small number of items
are ultimately presented for completion.
Edmund
