Merge pull request #5984 from jorisvandenbossche/doc-dtypes

DOC: correction of docstring dtypes/ftypes
API: Panel.dtypes to use generic method; add tests for Panel4D for same

DOC: updated api docs for panel/panel4d
DOC: in ReST, a sublabel defines it's parent. latex complains of dupe
Merge pull request #5985 from y-p/PR_doc_latex_fix

DOC: in ReST, a sublabel defines it's parent. latex complains of dupe
Merge pull request #5983 from jreback/panel_dtypes

API: Panel.dtypes to use generic method; add tests for Panel4D for same
DOC: add 0.13.1 whatsnew to the index
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
BUG: don't lose dtypes when concatenating empty array-likes
Merge pull request #5742 from immerrr/dont-lose-dtype-concatenating-empty-arraylikes

BUG: don't lose dtypes when concatenating empty array-likes
Merge pull request #5925 from y-p/PR_rebase_ipython_directive

Rebase ipython_directive on top of recent ipython updated version
DOC: document read_csv fastpath for iso8601 datetime strings
Merge pull request #5993 from y-p/PR_doc_iso8601_fast_path

DOC: document read_csv fastpath for iso8601 datetime strings
DOC: Document fast path in to_datetime GH4826
DOC: typos
Only recast if datetime; use astype instead of view
BUG: Fix to_datetime to properly deal with tz offsets #3944

Currently for certain formats of datetime strings, the tz offset will
just be ignored.