If an entry in the loop at `_tpl_metaheaders_action` has no content, skip this entry.

There are still some left in the DifferenceEngine code

this fixes another problem with our tests and phpunit 6.1

This fixes a problem with those tests in the most recent version of
phpunit. I thought it was caused by the use of the deprecated var
keyword, but some other weirdness was going on. This way it's more
proper anyway.

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.

This change breaks compatibility with php 5.3.7, but a standing
requirement for at least php 5.6 is declared in composer.json.

If the php documentation is to be believed, this change increases
security against pass-the-hash type attacks. (I do not have the knowledge
to assess the security differences between $2a$ and $2y$).

As a Sidenote: htpasswd shipped with apache2 2.4.10 (and probably,
other versions), when used with the -B (=bcrypt) option, produces hashes
marked with $2y$.

Nonewithstanding the actual support or non-support of $2a$ by the
apache2 'AuthUserFile' directive, the apache 2.4 documentation only
asserts support for the $2y$ bcrypt variant.
Therefore, this commit would make it possible for dokuwiki and apache2
basic authentication to share the same password file, in the case when
bcrypt is used.

* Updated remote.php

Updated remote.php for retrieving all the acl details.

* Updated remote.php

By mistake changed in addAcl instead of listAcls.

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.