DOC: Adding Panel docs to API, and shortening line length in panel.py
Merge branch 'panel_docs'

* panel_docs:
  DOC: Adding Panel docs to API, and shortening line length in panel.py
BUG: index.map fast path raises recursion warnings on index.time GH3419

PTF
Merge pull request #3450 from y-p/GH3419

BUG: index.map fast path raises recursion warnings on index.time GH3419
DOC: update comment
BUG: GH3449 .loc was not raising when passed an integer list

     PTF
Merge pull request #3451 from jreback/GH3449

BUG: GH3449 .loc was not raising when passed an integer list
ENH/CLN: redo pprint_warts merge, rebased PR lost the show
BUG: GH3448  Unordered time series selection was misbehaving when using label slicing
Merge pull request #3452 from jreback/GH3448

BUG: GH3448  Unordered time series selection was misbehaving when using label slicing
BUG: Removing a nonexistent store raises a KeyError
BUG: GH3455 Duplicate indexes with getitem will return items in the correct order

BUG: GH3457 to_csv writing duplicate columns incorrectly
Merge pull request #3447 from danielballan/remove-raises-keyerror

BUG: Removing a nonexistent store raises a KeyError (GH3346) - thansk!
Merge pull request #3459 from jreback/GH3455

BUG: GH3455 Duplicate indexes with getitem will return items in the correct order
TST: to_csv respects cols= reordering GH3454/7
BUG: to_csv handles cols= reordering,dupe cols GH3454/7
DOC: update RELEASE.rst

PTF
Merge pull request #3458 from y-p/GH3454

BUG: to_csv handles cols= reordering,dupe cols GH3454