Now underscores can be used to have sub actions. The loader will try to
find an exact match first, then begin removing parts from the end until
a matching action is found.

This is just a quick and dirty hack to try and see if the router
actually behaves as it should. I renamed the old methods to XXX_* and
implemented new ones calling the router. This has to be cleaned up
later.

It should now catch any circular loops (by having a maxiumum recursion
depth) and it handles the automatic redirect after save (and others)

This is not how integration of plugins would ideally be done in this new
system. Ideally an action plugin would actually implement an instance of
AbstractAction and would just fall into the normal flow of actions here.

However to not break a gazillion of existing plugins, this is just add
the existing two events into the new system through the use of a Plugin
action.

Maybe we could add "new" action plugins later.

Lots of FIXMEs and the routing isn't integrated, yet

This is neither complete nor working, yet

Those tests either just check that an exception is NOT thrown or are
there to check dependencies for other tests. Newer phpunits mark all
tests as risky that have no assertion.

I supplemented the existing comments on the methods in which there was not enough information to the standard phpDoc.

I supplemented the existing comments on the methods in which there was not enough information to the standard phpDoc.

I supplemented the existing comments on the methods in which there was not enough information to the standard phpDoc.

I supplemented the existing comments on the methods in which there was not enough information to the standard phpDoc.

squashed a whole bunch of PRs

closes #1907
closes #1908
closes #1909
closes #1910
closes #1911
closes #1912
closes #1913
closes #1914
closes #1915
closes #1916
closes #1917
closes #1918
closes #1919
closes #1920
closes #1921
closes #1922

actually we could right now. but I don't like to introduce that change in
a feature branch.

We still need 5 to test on old php versions, but travis uses 6 for newer
PHP versions (and 5 may break on those).

Luckily both versions aren't that far apart, yet. This adds a thin
adapter class when running on 6.

See for reference #1837 and sebastianbergmann/phpunit#2503

However those classes are already supported in PHP 5.7 so we can switch
to them without breaking backward-compatibility.

The documentation says sessionIDs are between 22 and 256 chars long. A
quick test only showed 26 chars in common configurations, but this
should cover all possibilities.