Merge pull request #4798 from jreback/clip

CLN: move clip to core/generic (adds to Panel as well), related to (GH2747)
CLN: move align out of series consolidating into core/generic.py
Merge pull request #4800 from jreback/series_align

CLN: move align out of series consolidating into core/generic.py
BUG: Fixed an issue with a duplicate index and assignment with a dtype change (GH4686)
Merge pull request #4806 from jreback/mi_assign

BUG: Fixed an issue with a duplicate index and assignment with a dtype change (GH4686)
DOC: some stylistic improvements to docstring rendering in documentation
CLN: removed need for Coordinates in HDFStore tables, instead return an Index of the coordinates
DOC: added section on select_as_coordinates
DOC: fix typos in missing_data.rst
Merge pull request #4809 from jreback/coordinates

CLN: removed need for Coordinates in HDFStore tables / added doc section
DOC: added .item() to __nonzero__ error message
DOC: correction of example in unstack docstring
DOC: add panelnd section to cookbook.rst
API: Complex compat for Series with ndarray. (GH4819)
Merge pull request #4820 from jreback/complex

API: Complex compat for Series with ndarray. (GH4819)
ENH: Allow abs to work with PandasObjects
Merge pull request #4821 from jtratner/add-__abs__-method

ENH: Allow abs to work with PandasObjects
DOC: doc build fixes
DOC: expand gotchas/basics on boolean reductions
ENH: support timedelta64[ns] as a serialization type in HDFStore for query and append (GH3577)
CLN: refactored locations of timedeltas to core/tseries/timedeltas (from a series of functions in core/common)