Add basis for path code

Hello everybody, this is mostly ready but still wip code that for the basis for paths in the state trackers. Verification and lookup should all be there. The only thing missing is the exact interface for attaching objects to the paths to point at and destroying all of them when the instance is freed. Comments please.

If people feels comfortable we can probably merge all of the aux/math and aux/util patches before the rest of the series goes in.

Cheers, Jakob.