Materialized view support

[taebow]

If there aren't impediments, I would like to add an option to the CreateView method to create materialized view.

[jklukas]

My general impression is that materialized views are a fairly implementation-specific concept with significantly different syntax per db. It may be more reasonable for individual dialects to implement appropriate constructs for materialized views.

sqlalchemy-redshift, for example, recently added support within the dialect for creating materialized views: sqlalchemy-redshift/sqlalchemy-redshift#202