- In the SQL Server pyodbc dialect, repaired the implementation
for the ``description_encoding`` dialect parameter, which when
not explicitly set was preventing  cursor.description from
being parsed correctly in the case of result sets that
contained names in alternate encodings.  This parameter
shouldn't be needed going forward.
fixes #3091

Conflicts:
	test/sql/test_unicode.py
- Added statement encoding to the "SET IDENTITY_INSERT"
statements which operate when an explicit INSERT is being
interjected into an IDENTITY column, to support non-ascii table
identifiers on drivers such as pyodbc + unix + py2k that don't
support unicode statements.
ref #3091 as this fix is also in that issue's patch, but is
a different issue.