Fix unititialized string offset access in query parser

The code always tried to access positon 2 of the parsed token, even for
tokens shorter than that (like OR)

fixes #3896

UnitTest around changelog, set correct time of page source

ChangeLog constructor will check the date of current page/media file to detect external edits via getCurrentRevisionInfo()

add needed type hints for phpunit8

This will break a lot of plugin tests, but can't be avoided

split changelog classes into their own namespace

The remaining functions in inc/changelog.php should be moved into a
utility class.

bugfix and reformatting changelog. small chunck unittests

improve unittests getrelativerevision. Bit code reformatting unit tests

fix not updated call, renaming

refactor PageRevisionLog into Media- and PageChangelog extending Changelog

Update changelog unit tests

Fixed file names of test classes