Remove header comments from all CPP files

[mifrandir]

Currently, every file has a comment at the top which gives general information like a description, the author and the licensing. While this is intended to be useful, it turns out that there is no point in keeping this.

• To find the last edit date and the authors, git blame or GitHub are far more useful and accurate and don't require any human input.
• The descriptions tend to be out of date or empty. Additionally, I would argue that such general documentation should be in the wiki.
• The license can be put at the top level of the directory. Since any code is copyrighted by default, and licenses only weaken those restrictions, there is no requirement whatsoever to make "absolutely doubly sure" that whoever may read the code is aware of the licensing. If they want to use it, they have to be aware of the license.

[mifrandir]

Fixed in #12