Remove unused flag supports_char_length.
Enable support for native decimal. Tested on LUW 9.7 and z/OS 9.1.
Use flags from superclass.

The makes it easier to tell when a dialect has a different flag than its
superclass.
Remove unnecessary CAST restriction.

See issue: http://code.google.com/p/ibm-db/issues/detail?id=104
Fix DB2 expression for SAVEPOINT.
Copy handling of OFFSET + LIMIT from mssql.
Use existing processors for Boolean type.
Render integer 1/0 instead of literal true/false.

http://www.sqlalchemy.org/trac/ticket/2682
Fix dropping of UNIQUE/CHECK constraint.
Fix retrieval of lastrowid when using pyodbc.
Driver should be either ibm_db, pyodbc, or zxjdbc.
Add dialects db2.ibm_db400, db2.ibm_dbz, db2.pyodbcz, and db2.zxjdbcz.

Also add a "flavor" attribute so that it is easier to differentiate between
DB2 for LUW, DB2 for iSeries, and DB2 for z/OS.
Fix the normalize_name method based on the one from oracle.

Previously, the "elif name != None" code path would likely not get executed.
Fix reflection of view definition.
Get the AS400 flavor to use its own reflector class.

Also remove possibly misleading comment.
Add reflection for the z/OS flavor.
Reflect TIMESTAMP column correctly on z/OS.
Restrict column alias length to 30 by default on z/OS.