[FEATURE] Drop CVS $Id$ stuff

[BenBE]

Is your feature request related to a problem? Please describe.
When looking at the code I noticed that it contains $Id: $ comments from the CVS days. As the source is currently managed in Git those markers are likely unused (unless Git has been set up to do content transforms, which is non-default behaviour).

Describe the solution you'd like
Thus I'd suggest to globally remove those $Id: $ content transform comments from the code base.

Describe alternatives you've considered
None. Leaving things as is will just lead to those comments staying untouched and thus out-of-date eventually.

Additional context
Cf. the section keyword expansion in the Git SCM manual

There has been some discussions of using keyword substitution with Git (e.g. linked in the FAQ, most of it advising against it.