[Zope] ODBC DA

[Jay, Dylan]

Currently the ODBC DA doesn't handle transactions to Level3 and therefore is
a major performance bottleneck on my sites. The reasoning for it not going
to level 3 I believe is because the ODBC spec doesn't state whether it is
thread safe or not. Surely some ODBC implementations must be thread safe. If
anyone knows which ones are could they say and then maybe we could have an
option in the ODBCDA to which level of transaction support we use.