Merge pull request #46 from vrajmohan/master

More fixes for cross references and reducing warnings (3rd wave)

diff --cc lib/sqlalchemy/dialects/oracle/cx_oracle.py
Simple merge

diff --cc lib/sqlalchemy/ext/declarative/__init__.py
Simple merge

diff --cc lib/sqlalchemy/sql/selectable.py
Simple merge

diff --cc lib/sqlalchemy/sql/sqltypes.py
Simple merge