- The typing system now handles the task of rendering "literal bind" values,
e.g. values that are normally bound parameters but due to context must
be rendered as strings, typically within DDL constructs such as
CHECK constraints and indexes (note that "literal bind" values
become used by DDL as of :ticket:`2742`).  A new method
:meth:`.TypeEngine.literal_processor` serves as the base, and
:meth:`.TypeDecorator.process_literal_param` is added to allow wrapping
of a native literal rendering method. [ticket:2838]
- enhance _get_colparams so that we can send flags like literal_binds into
INSERT statements
- add support in PG for inspecting standard_conforming_strings
- add a new series of roundtrip tests based on INSERT of literal plus SELECT
for basic literal rendering in dialect suite