ARM Scheduler Model: Partial implementation of the new machine scheduler model

This is very much work in progress. Please send me a note if you start to depend
on the added abstract read/write resources. They are subject to change until
further notice.

The old itinerary is still the default.
ARM Scheduler Model: Add resources instructions, map resources in subtargets

Move the CortexA9 resources into the CortexA9 SchedModel namespace. Define
resource mappings under the CortexA9 SchedModel. Define resources and mappings
for the SwiftModel.