Update changelog for 2.7.3 release

NEWS

+Version 2.7.3 (2018-05-09)
+==========================
+
+Data updates
+------------
+
+- Update tzdata to 2018e. (gh pr #710)
+
+
+Bugfixes
+--------
+
+- Fixed an issue where decimal.Decimal would cast `NaN` or infinite value in a
+  parser.parse, which will raise decimal.Decimal-specific errors. Reported and
+  fixed by @amureki (gh issue #662, gh pr #679).
+- Fixed a ValueError being thrown if tzinfos call explicity returns ``None``.
+  Reported by @pganssle (gh issue #661) Fixed by @parsethis (gh pr #681)
+- Fixed incorrect parsing of certain dates earlier than 100 AD when repesented
+  in the form "%B.%Y.%d", e.g. "December.0031.30". (gh issue #687, pr #700)
+- Fixed a bug where automatically generated DTSTART was naive even if a
+  specified UNTIL had a time zone. Automatically generated DTSTART will now
+  take on the timezone of an UNTIL date, if provided. Reported by @href (gh
+  issue #652). Fixed by @absreim (gh pr #693).
+
+
+Documentation changes
+---------------------
+
+- Corrected link syntax and updated URL to https for ISO year week number
+  notation in relativedelta examples. (gh issue #670, pr #711)
+- Add doctest examples to tzfile documentation. Done by @weatherpattern and
+  @pganssle (gh pr #671)
+- Updated the documentation for relativedelta. Removed references to tuple
+  arguments for weekday, explained effect of weekday(_, 1) and better explained
+  the order of operations that relativedelta applies. Fixed by @kvn219
+  @huangy22 and @ElliotJH (gh pr #673)
+- Added changelog to documentation. (gh issue #692, gh pr #707)
+- Changed order of keywords in rrule docstring. Reported and fixed by
+  @rmahajan14 (gh issue #686, gh pr #695).
+- Added documentation for ``dateutil.tz.gettz``. Reported by @pganssle (gh
+  issue #647). Fixed by @weatherpattern (gh pr #704)
+- Cleaned up malformed RST in the ``tz`` documentation. (gh issue #702, gh pr
+  #706)
+- Changed the default theme to sphinx_rtd_theme, and changed the sphinx
+  configuration to go along with that. (gh pr #707)
+- Reorganized ``dateutil.tz`` documentation and fixed issue with the
+  ``dateutil.tz`` docstring. (gh pr #714)
+
+
+Misc
+----
+
+- GH #674, GH #688, GH #699
+
+
 Version 2.7.2 (2018-03-26)
 ==========================
 

changelog.d/670.doc.rst

-Corrected link syntax and updated URL to https for ISO year week number notation in relativedelta examples. (gh issue #670, pr #711)

changelog.d/671.doc.rst

-Add doctest examples to tzfile documentation. Done by @weatherpattern and @pganssle (gh pr #671)

changelog.d/673.doc.rst

-Updated the documentation for relativedelta. Removed references to
-tuple arguments for weekday, explained effect of weekday(_, 1) and
-better explained the order of operations that relativedelta
-applies. Fixed by @kvn219 @huangy22 and @ElliotJH (gh pr #673)

changelog.d/674.misc.rst

-Add property testing with hypothesis with property tests for parserinfo.convertyear. Implemented by @coreygirard and @loldja (gh pr #674)

changelog.d/679.bugfix.rst

-Fixed an issue where decimal.Decimal would cast `NaN` or infinite value in a parser.parse, which will raise decimal.Decimal-specific errors. Reported and fixed by @amureki (gh issue #662, gh pr #679).
\ No newline at end of file

changelog.d/681.bugfix.rst

-Fixed a ValueError being thrown if tzinfos call explicity returns ``None``.  Reported by @pganssle (gh issue #661) Fixed by @parsethis (gh pr #681)

changelog.d/687.bugfix.rst

-Fixed incorrect parsing of certain dates earlier than 100 AD when repesented in the form "%B.%Y.%d", e.g. "December.0031.30". (gh issue #687, pr #700)

changelog.d/688.misc.rst

-Add a test for the property that ``dateutil.parser.parse`` will support inversion of ``datetime.isoformat()`` so long as ``sep`` is an ASCII character. Added by @pganssle (gh pr #688)

changelog.d/692.doc.rst

-Added changelog to documentation. (gh issue #692, gh pr #707)

changelog.d/693.feature.rst

-Fixed a bug where automatically generated DTSTART was naive even if a specified UNTIL had a time zone. Automatically generated DTSTART will now take on the timezone of an UNTIL date, if provided. Reported by @href (gh issue #652). Fixed by @absreim (gh pr #693).

changelog.d/695.doc.rst

-Changed order of keywords in rrule docstring. Reported and fixed by @rmahajan14 (gh issue #686, gh pr #695).

changelog.d/699.misc.rst

-Added unittest to check if tz's objects repr contains the "name" attribute of an input fileobject.
-Added by @Bergvca (gh pr #699)

changelog.d/704.doc.rst

-Added documentation for ``dateutil.tz.gettz``. Reported by @pganssle (gh issue #647). Fixed by @weatherpattern (gh pr #704)

changelog.d/706.doc.rst

-Cleaned up malformed RST in the ``tz`` documentation. (gh issue #702, gh pr #706)

changelog.d/707.doc.rst

-Changed the default theme to sphinx_rtd_theme, and changed the sphinx configuration to go along with that. (gh pr #707)

changelog.d/710.data.rst

-Update tzdata to 2018e. (gh pr #710)

changelog.d/714.doc.rst

-Reorganized ``dateutil.tz`` documentation and fixed issue with the ``dateutil.tz`` docstring. (gh pr #714)