sanity check thisPost before applying userTagger hardIgnore

ensure that user tagger found a valid post to hide when hardIgnoring somebody.

fixes #1898
sanity check that ignored user is author before ignoring post

fixes #1899
Nightmode wiki headers
Merge pull request #1900 from gavin19/master

Nightmode wiki headers
Added changelog for 4.5.3.
Merge pull request #1901 from KamranMackey/patch-1

Added changelog for 4.5.3.
Fixed a small typo in the changelog.
Merge pull request #1902 from KamranMackey/patch-2

Fixed a small typo in the changelog and added a few hugs.