Merge branch 'releases' into debian

* releases: (850 commits)
  RLS: v0.20.3
  TST/PKG: Move test HDF5 file to legacy (pandas-dev#16856)
  DOC: Final release notes
  CI: Pin to sphinx 1.5 for doc build
  DOC: Whatsnew updates (pandas-dev#16853)
  BUG: kind parameter on categorical argsort (pandas-dev#16834)
  BUG: allow empty multiindex (fixes .isin regression, GH16777) (pandas-dev#16782)
  BUG: fix missing sort keyword for PeriodIndex.join (pandas-dev#16586)
  DOC: Pin numpy at 1.11 for doc build
  MAINT: Remove fspath from 0.20.x branch
  BUG: TimedeltaIndex raising ValueError when slice indexing (pandas-dev#16637) (pandas-dev#16638)
  BUG: render dataframe as html do not produce duplicate element id's (pandas-dev#16780) (pandas-dev#16801)
  use network decorator on additional tests (pandas-dev#16824)
  BUG: rolling.cov with multi-index columns should presever the MI (pandas-dev#16825)
  BUG: Fix Series doesn't work in pd.astype(). Now treat Series as dict. (pandas-dev#16725)
  BUG: Fix read of py3 PeriodIndex DataFrame HDF made in py2 (pandas-dev#16781) (pandas-dev#16790)
  CI: use dist/trusty rather than os/linux (pandas-dev#16806)
  BUG: fix to_latex bold_rows option (pandas-dev#16708)
  Bug in pd.merge() when merge/join with multiple categorical columns (pandas-dev#16786)
  BUG: Load data from a CategoricalIndex for dtype comparison, closes #… (pandas-dev#16738)
  ...

Author: yarikoptic

.github/CONTRIBUTING.md

@@ -1,15 +1,18 @@
-#### A small, complete example of the issue
+#### Code Sample, a copy-pastable example if possible
 
 ```python
 # Your code here
 
 ```
+#### Problem description
+
+[this should explain **why** the current behaviour is a problem and why the expected output is a better solution.]
 
 #### Expected Output
 
 #### Output of ``pd.show_versions()``
 
 <details>
-# Paste the output here
+# Paste the output here pd.show_versions() here
 
 </details>

.github/ISSUE_TEMPLATE.md

@@ -1,4 +1,4 @@
  - [ ] closes #xxxx
  - [ ] tests added / passed
- - [ ] passes ``git diff upstream/master | flake8 --diff``
+ - [ ] passes ``git diff upstream/master --name-only -- '*.py' | flake8 --diff`` (On Windows, ``git diff upstream/master -u -- "*.py" | flake8 --diff`` might work as an alternative.)
  - [ ] whatsnew entry

.github/PULL_REQUEST_TEMPLATE.md

@@ -19,6 +19,7 @@
 .noseids
 .ipynb_checkpoints
 .tags
+.cache/
 
 # Compiled source #
 ###################
@@ -56,6 +57,8 @@ dist
 **/wheelhouse/*
 # coverage
 .coverage
+coverage.xml
+coverage_html_report
 
 # OS generated files #
 ######################
@@ -100,3 +103,5 @@ doc/source/index.rst
 doc/build/html/index.html
 # Windows specific leftover:
 doc/tmp.sv
+doc/source/styled.xlsx
+doc/source/templates/