CLN: Change assert_(a [not] in b) to specialized forms

Work on #6175. Changes instances of assert_(a [not] in b) to specialized assert[Not]In(a, b).
BUG: inconcistency in contained values of a Series created from a DatetimeIndex with a tz, related (GH6032)
ENH #6416: performance improvements on write - tradoff higher memory use for faster writes.
ENH: backport Python 3.3 ChainMap

ChainMap implements a list of mappings that effectively functions as a single
dictionary. This class is very useful for implementing scope. This commit also
adds a DeepChainMap subclass of ChainMap for writing and deleting keys.
CLN/ENH: use Scope.swapkey() to update names

Also useful for replacing local variable names with their mangled versions.
Merge pull request #6419 from jreback/series_tz_fix

BUG: inconcistency in contained values of a Series created from a DatetimeIndex with a tz
ENH/CLN: track scope instead of hard coding minimal stack level
ERR/API: disallow local references in top-level calls to eval
BUG: ChainMap m parameter only exists in Python 3.4

So backport that as well.
BUG: use a regular for loop in _ensure_term

In Python 3.x list comprehension build up stack frames, thus providing the
stack level to search is not the same as it is in Python 2.x.
Merge pull request #6366 from cpcloud/eval-fix-scope

ENH: fix eval scoping issues
REGR: Bug in Series.reindex when specifying a method with some nan values was inconsistent (noted on a resample) (GH6418)
Merge pull request #6421 from jreback/reindex_limit

REGR: Bug in Series.reindex when specifying a method with some nan values was inconsistent (GH6418)
ENH #6416 cleanup for PR
Merge pull request #6420 from mangecoeur/sql-perf

ENH #6416: performance improvements on write
ENH: Add functions for creating dataframes with NaNs
TST: windows dtype fix for test_series/test_reindex_pad
BUG: punt to user when passing overlapping replacment values in a nested dict
BUG: correctly tokenize local variable references
Merge pull request #6430 from cpcloud/eval-fix-at-containing-strings

BUG: correctly tokenize local variable references