Rector to rename print to echo calls

coding style: PSR12.Classes.ClassInstantiation.MissingParentheses

codestyle adjustments: class declaration braces

Apply rector fixes to inc/Action

Simplify event in denied action

Since there is no data manipulation, only allow suppresing the login form

Add event to denied action

Let plugins modify the text displayed on the denied page

fix handling of loading auth backend

When a non existing auth backend was configured, the action router ran
into an infinie loop exception. The reason was that the denied action
required a configure

fix handling of loading auth backend

When a non existing auth backend was configured, the action router ran
into an infinie loop exception. The reason was that the denied action
required a configured auth system, but denying access should always
work.

Interestingly the problem did not occur when the auth backend signalled
a failure to load. This was because the auth backend was not properly
deinitialized. This is now done.

To aid debugging similar problems, fatal errors are now logged through
the logging mechanism in the action router

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re-declare deprecated functions for backward compatibility

`dbg_deprecated()` is called in `html_diff_head()`, `html_diff_navigation()`, `html_diff_navigationlink()`, and following functions:

* `h

re-declare deprecated functions for backward compatibility

`dbg_deprecated()` is called in `html_diff_head()`, `html_diff_navigation()`, `html_diff_navigationlink()`, and following functions:

* `html_denied()` is not used any plugins, but added fallback just in case.
* `html_locked()` is used by one third-party plugin (AjaxEdit), fallback should be added.
* `html_insert_softbreaks()` is used by one third-party plugin (TOS, terms of service), fallback should be added.

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use $INPUT instead of $_SERVER

Remove Ui\{Denide, Locked} class

They are not UI components. We should show error message in Action\{Denide, Locked}::tplContent() methods.

Ui\Denid class replaces html_denid()

explicitly declare method visibility

more doc block fixes

start of a refactoring the action routing

This is neither complete nor working, yet