ENH: add display.max_seq_items to limit len of pprinted long sequences
TST: add test for com.is_sequence
Merge remote branch 'y-p/feature/limit_printing_long_seq'

* y-p/feature/limit_printing_long_seq:
  TST: add test for com.is_sequence
  ENH: add display.max_seq_items to limit len of pprinted long sequences