not perfect, but it works

Access attempts to security.png are normally denied, so the name of the file will be more self-descriptive

The empty string is not translatable in the translation interface and
causes all languages to be <100%

This is an alternative approach to #2164

There was a bug, where the options array ['Auto', 0, 1] would result in
HTML option tags where both the 'Auto' and the 0 option were selected.

This commit fixes a bug in the media manager when viewing an old version
of a media file. While, in case of an image, the old image would be
displayed in the third pane, the link above would still link to the
current version.

STREAM_CRYPTO_METHOD_TLS_CLIENT is only TLS 1.0 except for PHP 5.6.0-5.6.6 and 7.2.0+.

This fixes plugins that expect that they can change the global $ACT
instead of $event->data in the ACTION_ACT_PREPROCESS event.

This make the whole route a little bit uncleaner but would increase
backwards compatibility.

I'm not sure how widespread the problem is and if adding this is a good
idea.

This should recreate the behaviour prior to #1933, where the event was
triggered for all ACT values. Some plugins, like edittable, depend on
the functionality.

Since the hid is optional, it must also be optional in the regex. Also
this commit introduced named capture groups to make it more obvious
which part of the regex captures what.

Also there is now an explicit hid generated for tables, to enable
jumping to the correct section after finishing editing.

This was broken in 2571786c or #1966
respectively.

Known Issues:
* since both title and hid are optional, a hid may be misinterpreted as
a title if the title is not generated.

Exits during testing will break the whole test suite. It makes more
sense to throw an exception in that case. The exception's stack trace
will help to debug the actual problem