Merge remote-tracking branch 'origin/master' into new_utf8
Sql.FutureResult: Improve error reporting in case of failed queries.
Merge remote-tracking branch 'origin/8.1' into gobject-introspection
Sql.FutureResult: Rename raw_data -> data, and data -> get().
Sql.Promise: Improve docs.
Sql.Promise: New & improved interface.
Sql.FutureResult: Polish docs and internals; uses status_command_complete instead of exception.
Sql.FutureResult: Module was missing from the commits.