BUG: Fix corner cases in the pipeline browser: objects for which the number of inputs is misreported, and iterable objects to do not contain  TVTKBase entries.
BUG: Fix corner cases in the pipeline browser: objects for which the
number of inputs is misreported, and iterable objects to do not contain 
TVTKBase entries.



alexandreleroux/mayavi,liulion/mayavi,dmsurti/mayavi,alexandreleroux/mayavi,liulion/mayavi,dmsurti/mayavi