Merge pull request #4756 from jreback/nested

BUG/ER:  (GH2702) Bug with Series indexing not raising an error when the right-hand-side has an incorrect length
BUG: Bug with reindexing where a non-unique index will now raise ValueError (GH4746)
CLN: refactored out take from core/frame.py to use core/generic.py version