[Cake] Using firewall connmarks as tin selectors

[Toke Høiland-Jørgensen]

> I also equally aware that this is ‘creeping featuritis’ and doing
> nothing to speed cake up…

Yeah, this is the crux of the issue, really: it's a tradeoff between
ease of use and featuritis. Now in this case the actual impact is a
single check it might actually be acceptable

> actually I may have improved BESTEFFORT a little - we no longer look
> for matching TC Major numbers if there’s no actual choice of tin to be
> made :-)

Well, you made the besteffort case slightly faster, but every other mode
slightly slower... :)

If you are going to send a patch (or pull request), please leave out the
refactoring, and only include the feature. This makes it easier to see
the impact of the feature addition on its own.

Also, I assume you have a companion patch for iproute2 somewhere?

-Toke