per-package-family package orderers needed

I have a case where I want to use the TimestampPackageOrder class, but I need different orders depending on the package family.

One approach would be to add an optional packagename arg to this orderer, but that's unoptimal - to use 10 different oderers over 100 different packages, we'd have to iterate over the 10 orderers for every package.

Instead I think it makes sense to add a new orderer, PerFamilyOrder, where you can associate other Orderers with separate families (and be able to specify a default for all packages that don't have a specific orderer applied). This means applying to each package only involves a dict lookup - but more specifically, this is probably a common pattern, that this orderer will now allow us to apply to many situations involving different orderers.