DOC: CONTRIBUTING.md: Gold plating: syntax, punctuation, Markdown
TST: Tests and fix for unhandled data types in Excel writers.

Added tests and a fix for unhandled numpy data types in the
Excel writers. Issue #3122.
DOC: timeseries.rst updates
TST: use default utf8 encoding when passing encoding to parser as Bytes (GH5141)
Merge pull request #5149 from jreback/sparc_fix3

TST: use default utf8 encoding when passing encoding to parser as Bytes (GH5141)
TST/CI/BUG: fix borked call to read_html testing code
Merge pull request #5151 from cpcloud/read-html-lxml-skips

TST/CI/BUG: fix borked call to read_html testing code
DOC: 5143 (read_html testing bug) release notes
DOC: minor doc correction (issue number) from the previous commit
Merge pull request #5086 from westurner/patch-2

DOC: CONTRIBUTING.md: Gold plating: syntax, punctuation, Markdown format...
BUG: convert replacement tuples to lists

This fixes a bug that makes it appear as if replace is incorrectly using
regular expressions.
Merge pull request #5145 from cpcloud/replace-exact-fix

BUG: allow tuples in recursive call to replace
BUG: Fix to_datetime() uncaught error with unparseable inputs #4928
API/CLN: provide isnull/notnull on NDFrame objects
PERF: remove auto-boxing on isnull/notnull
Merge pull request #5154 from jreback/perf

PERF: remove auto-boxing on isnull/notnull
Merge pull request #5157 from danbirken/gh4928

BUG: Fix to_datetime() uncaught error with unparseable inputs #4928
DOC: Added filtering example to groupby doc

Filtering example for dataframe with > 2 fields -- filtering collapses
to dataframe, not series.
API/PERF: restore auto-boxing on isnull/notnull for Series (w/o copy) preservers perf gains
Merge pull request #5159 from jreback/isnull_box

API/PERF: restore auto-boxing on isnull/notnull for Series (w/o copy) preserves perf gains
DOC:  Move qt interface instructions to faq.rst from visualization.rst