failing buildbots.

related to ttk.

  protocol numbers are supplied outside the allowed 0-65536 range on bind()
  and getservbyport().

inside its source path if it began with the same letters (e.g. "src" vs.
"src.new").

Correct docs for ABCs (MutableSequence was missing __setiem).  Simplify the table by taking out inherited requirements for abstract methods.

for Iterator and MutableSet.  Also added thorough test for
required abstractmethods.