BUG: to_json should raise exception for non-unique index / columns (#4359)
Fix typo.

Change 'highlites' to 'highlights'.
TST/BUG: fix NameError in network decorator
DOC: release notes
CLN: remove some space
Merge pull request #4380 from daydreamt/patch-2

Fix typo.
Merge pull request #4381 from cpcloud/undefined-runs-in-network-decorator

TST/BUG: fix NameError in network decorator
Merge branch 'ujson-unique-keys' of https://github.com/Komnomnomnom/pandas into Komnomnomnom-ujson-unique-keys
DOC: release notes on GH4359 to_json change
BUG: fix period index object instantiation when joining with self
DOC: add release notes