code style: line breaks

coding style: function call spacing

Apply rector fixes to the rest of lib/plugin

another go at #3717

c0ece86a0ac0cfab0856b056fb3ce8e726855542 was wrong too, because most
deprecation logs drop the callee

Another fix for #3717

The deprecation mechanism did actually log the wrong file (callee
instead of caller). This was fixed and the message adjusted again.

A guardian for very short backtraces and l

Another fix for #3717

The deprecation mechanism did actually log the wrong file (callee
instead of caller). This was fixed and the message adjusted again.

A guardian for very short backtraces and large offsets was added

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better deprecation message for require. fixes #3717

adjust callstack depth for deprecation message further

better deprecation messages for self required plugin base files

First go at moving the plugin classes into their own namespace

Introducing a new Plugin type: CLI

Now plugins can create their own command line interfaces. They are
executed through a single entry point in bin/plugin.php