Issue 11616 - Introduce virtual keyword

Introduce the virtual keyword
Remove rdmd.1 man page.

This man page belongs to the tools repository.
Merge pull request #2895 from yebblies/issue11616

Issue 11616 - Introduce virtual keyword
Merge pull request #3333 from leandro-lucarella-sociomantic/rm-rdmd.1

Remove rdmd.1 man page.