SQLite support, including EXPLAIN and FTS4 fulltext search
Make contrib/bzdbcopy.pl actually work with anything other than Pg,
independent of current localconfig.

Never use Bugzilla->dbh in Bugzilla::DB::Schema, store and use $self->{dbh} instead.
Replace LEFT JOIN with INNER JOIN whenever it's possible

This only has profit for SQLite; no profit for normal databases.