add needed type hints for phpunit8

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

First go at moving the plugin classes into their own namespace

fixed broken tests

I also introduced an auto loaded namespace for the tests.

replace some var keywords

This should fix some tests on PHP 7.1. The work is far from done, we
still have a lot of variables without proper accessibility defined.

Merge branch 'master' into future

* master: (162 commits)
fixed revision JS for images
upgraded SimplePie to 1.3.1 FS#2708
removed obsolete browser plugin (migrate does it)
adjust spacing to

Merge branch 'master' into future

* master: (162 commits)
fixed revision JS for images
upgraded SimplePie to 1.3.1 FS#2708
removed obsolete browser plugin (migrate does it)
adjust spacing to match standard 1.4em grid
added comment on use of whitelist vs blacklist
Updated idfilter() function for IIS
use var and remove suggestions when needed Use variable for maximum number of suggestions for quicksearch. And hide suggestions when search field is emptied, or when no suggestion are found.
added 'home' class to first link in hierarchical breadcrumbs
reduced required max width to go into tablet mode
re-added linear gradients for firefox
added missing styling for disabled form elements (FS#2705)
fixed acronyms in italics (FS#2684)
improved print styles (includes fixes for FS#2645 and FS#2707)
basic styles improvements
Greek language update
Use list in acl help text, for more structure
Galician language update
touch the config on save, even if no changes were made
unwind the width narrowing commit
put some whitespace between form submit button and fieldset bottom border
...

Conflicts:
lib/plugins/config/admin.php
lib/plugins/config/settings/config.class.php

show more ...

use correct setUp method and parent calls.

fixed auth related tests

fixed group wildcards and added tests

removed unecessary requiresin unit tests

moved _testing to _test