Use correct test for paths vs lockers; fix -f

- Per the man page, something is a path (not a locker) if it
  starts with '.' or '/'
- Adding a path now honors "-f" rather than always appending
Merge branch 'master' into debian
Release and package 10.4.6

* Update to 10.4.6, which contains a fix for add's handling of local
  paths (Trac: #1465)