the  python 3 merge, now does not expect percent signs (e.g.
as used as the modulus operator and others) to be doubled,
even when using the "pyformat" bound parameter format (this
change is not documented by Mysqlconnector).  The dialect now
checks for py2k and for mysqlconnector less than version 2.0
when detecting if the modulus operator should be rendered as
``%%`` or ``%``.
- Unicode SQL is now passed for MySQLconnector version 2.0 and above;
for Py2k and MySQL < 2.0, strings are encoded.  Note that mysqlconnector
as of 2.0.1 appears to have a bug with unicode DDL on py2k, so the tests here
are skipping until we observe it's fixed.
- take out profiling on mysqlconnector, callcounts vary too much with
its current development speed

defaults if otherwise unspecified; the limitation where non-
server column defaults aren't included in an INSERT FROM
SELECT is now lifted and these expressions are rendered as
constants into the SELECT statement.

the sql package would fail to ``__repr__()`` successfully,
due to a missing ``description`` attribute that would then invoke
a recursion overflow when an internal AttributeError would then
re-invoke ``__repr__()``.
fixes #3195

method :meth:`.Query.with_statement_hint` to support statement-level
hints that are not specific to a table.
fixes #3206