schemas/vegbien.sql: materialize_query(): support schema-qualified tables. this requires escaping tables in calls to this function.

schemas/vegbien.sql: added rematerialize_out_view(in_view regclass)

schemas/util.sql: added qual_name()

schemas/vegbien.sql: added rematerialize_out_view(datasource_schema text, out_view regclass)

bugfix: schemas/vegbien.sql: source_by_shortname(): added schema_anchor so that it always applies to the schema it's defined in, even if `public` is not in the search_path

schemas/vegbien.sql: functions with schema_anchors: documented that they must use LANGUAGE plpgsql because LANGUAGE sql does not support runtime changes of search_path (schema elements are bound at inline time rather than runtime)

bugfix: schemas/vegbien.sql: functions with schema_anchors: must use plpgsql for these because the sql language does not support runtime changes of search_path (the schema elements they use are bound at inline time rather than runtime)

schemas/vegbien.sql: schema_null param: renamed to schema_anchor to clarify what this is for

fix: schemas/vegbien.sql: schema_null: clarified that this should always be left as the default value, not just usually

schemas/vegbien.sql: schema_null params: use schema_anchor instead of source for this, since it is guaranteed to exist regardless of which tables are in the VegBIEN schema