This modifies the Oracle ROWNUM limit/offset approach
to accommodate for the "OF" clause in a "FOR UPDATE"
phrase.  The column expressions must be added to the selected
subquery if necessary and adapted on the outside.

Change-Id: Ia71b5fc4df6d326e73863f8ae9f96e8f1a5acfc1
Fixes: #3741

Change-Id: I98cd60b6830ee94e39ba9307523a9e8fb93bf4e8
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/280

This adds `SELECT ... FOR UPDATE SKIP LOCKED`/
`SELECT ... FOR SHARE SKIP LOCKED` rendering.

Change-Id: Id1dc4f1cafc1de23f397a6f73d54ab2c58d5910d
Pull-request: https://bitbucket.org/zzzeek/sqlalchemy/pull-requests/86

cx_Oracle connection parameters user, password and dsn must be
either a string or NULL.  When they are passed a Python None object,
"TypeError: expecting string, unicode or buffer object" is raised.

Fixes: #3705

Change-Id: I8da5d8a227ca12c9bf17a6127460e413841951fb
Pull-request: https://github.com/zzzeek/sqlalchemy/pull/271

on unicode.   Enum would be better as a TypeDecorator
at this point but then that becomes awkward with native enum
types (Interval works that way, but we don't need the bind_processor for
native interval...)