"binds" (e.g. engines to use), such engines can be associated with
mixin classes, concrete subclasses, as well as a wider variety
of table metadata such as joined inheritance tables.
fixes #3035

ORM functions that are derived as "public factory" symbols, which
should assist with documentation tools being able to report on the
target module.
fixes #3218

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

take that out, restore the better exception logic in exc