* Added SQLAlchemy annotations
* Made Connection and Engine sublcasses of Connectable (python/typeshed#1018)
* Moved execute() from Connection to Connectable
* Made RowProxy a Mapping and removed Mapping inherited methods
* Made ResultProxy an Iterator of RowProxy
* Added most relevant methods for fetching of ResultProxy
* Added where(), group_by(), order_by() and limit() to Select
* Follow squalchemy module structure
* Created sqlalchemy.engine.result and moved ResultProxy and RowProxy
there
* Created sqlalchemy.engine.interfaces and moved Connectable there
* Added non-deprecated methods to Connectable: connect,
contextual_connect and scalar
* Fixed return type of scalar() to Any
* Missed ResultProxy scalar return
... had it in Connectable only.
