DatabaseAPI and DatabaseConnector

v 0.4.1:

- Removed dependency on a user authentication feature that is new
to Zope 2.1.5 (verify_watermark()).  Should work on earlier versions
of Zope now.

v 0.4:

- Added the ability to have "protected" members in a DatabaseConnector.
Protected members can't be accessed through a virtual context, but
when any public method of the database is called, the context is
switched in such a way that the method can access protected methods.

- Minor bugfixes related to TinyTable support within a
DatabaseConnector.

v 0.3:

- Made a major correction in the way DatabaseConnector creates a
virtual context for databases.  Acquisition was incorrectly
implemented.

- Removed the "localGroupNames" hack.  From now on, databases will
get objects from the virtual context just by using acquisition.

- Made it so DatabaseConnectors inside DatabaseConnectors will
acquire correctly from the parent DatabaseConnector, then the
original virtual context.  This is very important for the change
in ACLManager that promotes modularity by using multiple
inter-accessible databases.

- Added author, version, and apidesc properties to DatabaseAPI.

- Modified the method DatabaseAPI uses to determine what permissions
are no longer in use.  The "cleanup" list will be shorter and more
accurate now.
