Updated to ZODB 3.9.0a10. ZODB-level version support has been removed and ZopeUndo now is part of Zope2.

Put back the defaultSkin directive. I misread the comments and only the other two directives in the misc section where deprecated.

from a meta-equiv header

Updated to newer versions of zope packages. Removed long deprecated defaultSkin, layer and skin ZCML directives.

for making Zope 2.12 run with ZODB 3.9 (having ZopeUndo removed)

  however is still available on the Python level.