Sort source files by functionality, not by type

[thusser]

Sorting all source files into different folders, named by functionality ("astro", "telescope", "focus", ...) instead of type (POUs, ...) would increase readability a lot.

[weingrill]

The main issue is the transfer of GVL I/O variables. Maybe they can be moved by using refactoring or (simply) by "drag&drop", which has to be tested.
The source files and folder structure should represent the hardware units nonetheless. This is naturally true for the Safety Unit.