ENH: add last element to repring of sequences
the mutual recursion should bottom out in `_pprint_seq` during either the call to `next` (will raise `StopIteration`) or it will raise `StopIteration` when `i not in range(min(nitems, len(seq)))`. i will also change that to `xrange` because that will be a memory hog for large sequences with the default option. in any case i will write more tests and i still need to fix the unicode literal repring
 should i be using `pprint_thing` anytime (even a trivial string) i'm formatting a string?
 `pprint_thing` is actually all about doing unicode properly. whenever you have something
that goes to the console, it's best to use pprint_thing. using it also makes sure
things are kept as unicode until it's time to encode them into a specific encoding.
 well that's just dandy! thanks
 @y-p @jreback u ok with this?
 what does this fix?
 just tacks on the last element of a sequence when the user has set max_seq_items to something > 0
 ok as long as @y-p ok
 related #3456, #3391 and especially https://github.com/pydata/pandas/issues/3426,
would have preferred matching behaviour to numpy: [Foo_N ... Foo_N]
 I can do that. No problem. 
 @y-p N is the `display.max_seq_items` option value? should it be N / 2?
 no preference, if possible align with numpy, I believe it has an equiv in set_printoptions.
 closing in favor of #3974.
