Merge pull request #7572 from jaimefrio/rolling_var_bug

BUG: Error in rolling_var if window is larger than array, fixes #7297
TST: fixes for 2.6 comparisons
Revert "Merge pull request #7591 from mcwitt/parse-index-cols-c"

This reverts commit 2c603e17b60665b5db6b373f33e1479f47b7155a, reversing
changes made to 49a86f1fb90ea199cba0954ede6b939f672867b1.
PERF: allow dst transition computations to be handled much faster
      if the end-points are ok (GH7633)
PERF: allow slice indexers to be computed faster
Merge pull request #7652 from jreback/dst_transitions

PERF: fix perf issue in tz conversions w/o affecting DST transitions
API: disallow inplace setting with where and a non-np.nan value (GH7656)
Merge pull request #7657 from jreback/where

API: disallow inplace setting with where and a non-np.nan value (GH7656)
BUG: DatetimeIndex.delete with tz raises ValueError
BUG: consistent subplot ax handling
Merge pull request #7608 from sinhrks/delete2

BUG: DatetimeIndex.delete with tz raises ValueError
TST/CLN: Refactor io.data.options class to improve testing

Removed most references to month and year (passing expiry date around instead).
Also protected with RemoteDataError checking for the expiry month links.
BUG: Bug in multi-index slice setting, related GH3738
Merge pull request #7667 from jreback/mi_slicing

BUG: Bug in multi-index slice setting, related GH3738
BUG: windows failure on GH7667
Merge pull request #7668 from pydata/mi_slicing2

BUG: windows failure on GH7667
BUG: area plot raises ValueError with tz-aware data
Merge pull request #7515 from sinhrks/areabug

BUG: area plot raises ValueError with tz-aware data
BUG/CLN: LinePlot uses incorrect xlim when secondary_y=True
Update docs to use display.width instead of deprecated line_width.