This change includes mainly that the bracketed use within
select() is moved to positional, and keyword arguments are
removed from calls to the select() function.  it does not
yet fully address other issues such as keyword arguments passed
to the table.select().

Additionally, allows False / None to both be considered
as "disable" for all of select.correlate(), select.correlate_except(),
query.correlate(), which establishes consistency with
passing of ``False`` for the legact select(correlate=False)
argument.

Change-Id: Ie6c6e6abfbd3d75d4c8de504c0cf0159e6999108

Added support for PostgreSQL "readonly" and "deferrable" flags for all of
psycopg2, asyncpg and pg8000 dialects.   This takes advantage of a newly
generalized version of the "isolation level" API to support other kinds of
session attributes set via execution options that are reliably reset
when connections are returned to the connection pool.

Fixes: #5549
Change-Id: I0ad6d7a095e49d331618274c40ce75c76afdc7dd

The isolation level section in the docs inadvertently
copied the PostgreSQL example using the PGDialect.isolation_level
parameter and not the execution_options.  ensure only
the execution_options version is documented.

Change-Id: I94e02ede62d3dded40e3fcbce8d04608dc063108

Two operations have been defined:

* :meth:`~.ColumnOperators.regexp_match` implementing a regular
  expression match like function.
* :meth:`~.ColumnOperators.regexp_replace` implementing a regular
  expression string replace function.

Fixes: #1390
Change-Id: I44556846e4668ccf329023613bd26861d5c674e6

MariaDB should not run a Sequence if it has optional=True.
Additionally, rework the rules in crud.py to accommodate the
new combination MariaDB brings us, which is a dialect
that supports both cursor.lastrowid, explicit sequences,
*and* no support for returning.

Co-authored-by: Mike Bayer <mike_mp@zzzcomputing.com>
Fixes: #5528
Change-Id: I9a8ea69a34983affa95dfd22186e2908fdf0d58c

The _execute_20 and exec_driver_sql methods should wrap
up the parameters so that they represent the single list / single
dictionary style of invocation into the legacy methods.  then
the before_ after_ execute event handlers should be receiving
the parameter dictionary as a single dictionary.   this requires
that we break out distill_params to work differently if event
handlers are present.

additionally, add deprecation warnings for old argument passing
styles.

Change-Id: I97cb4d06adfcc6b889f10d01cc7775925cffb116