DOC: updated dtypes docs
Merge pull request #2947 from jreback/dtypes_doc

DOC: updated dtypes docs
BUG: in-place conversion of integer series to float (on putmasking), GH #2746
CLN: argument order and dtype formatting to be consistent with standard
BUG: negative timedeltas not printing correctly
ENH: timedelta ops with other timedelta fixed to produce timedeltas

BUG: fixed timedelta (in nanops.py) to work with min/max....abs still not working
BUG: issue with timedelta64 and numpy 1.6.1 (used on travis), fixed by using views
Merge pull request #2950 from jreback/intna_2746

BUG: in-place conversion of integer series to float (on putmasking), GH #2746.
Merge pull request #2951 from jreback/series_dtype

CLN: argument order and dtype formatting to be consistent with standard
Merge pull request #2955 from jreback/timedelta_issues

BUG: negative timedeltas not printing correctly
BUG: changed Dtype to dtype on series displays
Merge pull request #2959 from jreback/series_dtype2

BUG: changed Dtype to dtype on series displays