TODO: more pprint imporvements
#### TODO
- [ ] dicts with many keys should be summarized (Update: I can no longer remember the use case for dicts
  printed via pprint_thing).
- [ ] summarization should match numpy [a.a.a ... b b b] not [a a a ...]
- [ ] add np.set_printoptions(edgeitems) analogue.

<del>
- [ ] options.display.max_seq_items should have a default value != None #3391, #5120 , #5629 
</del>

via https://github.com/pydata/pandas/pull/5753
