BUG: resample raises ValueError when NaT is included
DOC: Add how to calculate month-start to cookbook

Related: #7449
BUG: DTI.intersection doesnt preserve tz
BLD: use sqlalchemy 0.7.1 in 2.6 build (GH6340)
Merge pull request #7455 from shoyer/month-start-cookbook

DOC: Add how to calculate month-start to cookbook
Merge pull request #7022 from jreback/sqlalchemy

BLD: use sqlalchemy 0.7.1 in 2.6 build (GH6340)
Merge pull request #7373 from sinhrks/resamplenat

BUG: resample raises ValueError when NaT is included
Merge pull request #7458 from sinhrks/intersection

BUG: DTI.intersection doesnt preserve tz
ENH/API: offsets now accepts datetime64
Merge pull request #7452 from sinhrks/offsets_dt64

ENH/API: offsets funcs now accepts datetime64
BUG: astype(float) in Index does the wrong thing
Merge pull request #7464 from cpcloud/float64index-bad-construction

BUG: astype(float) in Index does the wrong thing
BUG/CLN: LinePlot uses incorrect xlim when secondary_y=True