BUG: use the "join" string in Appender decorator

The docstring for Appender decorator says that "join" parameter is used to join the docstring and addendum.  This commit brings the code in line with the documentation.
DOC: tutorials
DOC: whitespace fixes for tutorials update GH5929
Change "methdo" to "method" in asfreq's docstring.
Merge pull request #5989 from  adeodatus/master

* adeodatus-master:
  Change "methdo" to "method" in asfreq's docstring.
Merge pull request #5959 from gandalf013/master

BUG: use the "join" string in Appender decorator
ENH: Add array_equivalent, to address the handling of NaNs when comparing arrays for equality.

Added NDFrame.equals

Index, Float64Index, and MultiIndex's equal method now uses array_equivalent
instead of np.array_equal.
Goal: do not deteriorate performance by a factor of 7
Let Index use np.arary_equal by default.
Add a new method, `equivalent`, for handling NaNs.
Try using isnan
BUG: The change in array_equivalent makes it not work on object arrays.

To to salvage some usefulness in NDFrame.equals, we must loop to check
each column of the NDFrame separately.
TST: Add a dataframe with object, float and datetime64[ns] columns, each containing NaNs.
TST: Add test for complex arrays
Add check for Int64Index
Using changes suggested by jtratner
Move test_equals to tests/test_generic.py
Revert index.py to master (Don't use array_equivalent)
Use isnull if left or right is an object array. Otherwise, use isnan.
TST: Test that array_equivalent treats NaN the same (as equal) in object as well as float arrays