Bugfix: Account for rules sorted after unmanaged rules

The offset calculation assumed unmanaged rules are numbered 9000+ and
would be sorted to the end and didn't need to be accounted for. This
caused failures when people used9-numbered rules. This should fix that.

Additionally, for rules that are 9-numbered, they should be ordered
*after* unmanaged rules, so this fixes that too.

So when encountering unmanaged rules, the order will be something like
this:

- Managed rules that begin with 0 through 8
- Unmanaged rules (which are assigned 9-numbers)
- Managed rules that begin with 9 (but not numbered lower than the
  unmanaged rules)

Mixing unmanaged rules with managed rules is still not officially
supported, but at least we can try and behave with them.
Merge pull request #321 from hunner/fix_over_9000

Bugfix: Account for rules sorted after unmanaged rules