Get file header comments and similar up to date

[Moppa5]

Description
As a part of the cleanup project it was mentioned that Seravo Plugin contains a lots of outdated file header comments. There were lots of parts and code that was not documented before we run the rector. However, we should investigate and decide whether we remove those file header comments, versions etc. or get them up to date.

Personally I think that it would be nice to have method comments and documentation of every module or interface in general. On the other hand, I don't know how valuable the version of each module is? Could there be just general description of the class and its duties?

[Moppa5]

#596 is related to this as it includes plenty of changes to the class comments. Most of the file headers contain now only the class comment and nothing more. As discussed I think we should stick with the class comments only. I don't think the separate version comments for each module do the job very well.