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