pylint #104420 check for protocol completness and avoid false R0903 [validation pending]

see http://lists.logilab.org/pipermail/python-projects/2012-February/003169.html

prioritynormal
typeenhancement
done in0.26.0
load1.000
load left0.000
closed by#6416aabd2d6a integrate patch from Peter Hammond to check protocol completness and avoid false R0903. Closes #104420