- Unit tests pass 100% on MySQL installed

- Unit tests pass 100% on MySQL installed
on windows, after aggressive exclusion of a wide variety
of tests.   Not clear to what degree the failures are related to
version 5.5 vs. the usage of windows, in particular the ON UPDATE CASCADE
immediately crashes the server.   The features being tested here are all
edge cases not likely to be used in typical MySQL environments.
- Removed the "adjust casing" step that would
fail when reflecting a table on MySQL
on windows with a mixed case name.  After some
experimenting with a windows MySQL server, it's
been determined that this step wasn't really
helping the situation much; MySQL does not return
FK names with proper casing on non-windows
platforms either, and removing the step at
least allows the reflection to act more like
it does on other OSes.   A warning here
has been considered but its difficult to
determine under what conditions such a warning
can be raised, so punted on that for now -
added some docs instead. [ticket:2181]

- supports_sane_rowcount will be set to False
if using MySQLdb and the DBAPI doesn't provide
the constants.CLIENT module.