* limited update/delete now works on views with explicit order
* no default order, enforce order presence
* apply row count to ensure limited mutations
* move requiring order to ApiRequest
Only add m2m relationship based on real junctions:
a table has FKs to two other tables and the FK columns
are part of the PK columns.
Also add some stats to big_schema.sql
Aggregates and Window functions can't be called as RPCs in a useful way.
Procedures are not supported right now, but might be added later.
Resolves#2101
Signed-off-by: Wolfgang Walther <walther@technowledgy.de>