[fw-db] Zend_Db_Select from() & join() fixes

Hey all,

I have updated Zend_Db_Select to fix a problem several people might have
experienced in one form or another (specifically when trying to use
Zend_Auth_Adapter_DbTable::getDbSelect() to join against).

The issue is here:
http://framework.zend.com/issues/browse/ZF-6653

And the fix is in trunk as of r18475.

This fix passes all previous unit tests. While I cannot conceive of a
use case that it would break (stright up or by extending
Zend_Db_Select), and also since the fix is so extensive, I'd like to
make sure no one has issues with it before merging in the 1.9 branch.

Thanks in advance!
-ralph