Now it's restored, and the unit-tests are functional again:
* The `pysqlite_to_sql` function has been made available so that
we can build the InMemoryConnection class, which is inheriting
either from PySQLite2Connection or PySQLite1Connection if the
former is not available
* The trac/tests/db.py has been moved in trac/db/tests/db.py
* but there are still 2 env related tests that are failing...
Also, in r2492, I forgot to port r2426 to pysqlite.py