markupsafe: Initial commit

git-svn-id: svn+ssh://svn.code.sf.net/p/gar/code@23101 d3b55034-1cff-0310-a425-aefe953e1e90
find-obsolete-pkgs: Adapt to the new code

Additional changes:

- Instead of sometimes using CatSubSet and sometimes pkgname, let's always use
  CatSubSet
- Split the code into smaller functions

TODO ideas:
1. Provide a per-maintainer report, so people can know what they can drop or
   rebuild.
2. Use the for-generation REST endpoint, because it's fast and provides all
   the information necessary for calculation, and avoids the problem with
   reverse dependency cache being stale.

git-svn-id: svn+ssh://svn.code.sf.net/p/gar/code@23102 d3b55034-1cff-0310-a425-aefe953e1e90