- doesn't make a difference here, but the right API method for getting the user ID is getId, not getUserName

svn+ssh://svn.zope.org/repos/main/Zope/branches/2.12 r118262:118470

Fixes LP #628448.

Forward-port from 2.13 branch.

Dropped the direct dependencies on packages that have been factored out of the main Zope 2 tree. Make sure you declare a dependency in your own distribution if you still use one of these: ``Products.BTreeFolder2``, ``Products.ExternalMethod``, ``Products.MailHost``, ``Products.MIMETools``, ``Products.PythonScripts`` or ``Products.StandardCacheManagers``.

Avoid conflict error hotspot in PluginIndexes' Unindex class by using IITreeSets instead of simple ints from the start. Idea taken from ``enfold.fixes``. This optimizes the common case of FieldIndexes being used for a low number of unique values. The edge-case of having a FieldIndex for an unique value per document gets penalized, as it uses many more persistent objects. This really warrants a separate type of index.