this draft is based on
- Cehteh's draft for the scheduler
- my plannings about segmentation and JobTicket
it defines "Job" as a closure which can be invoked
from plain-C, using the information in the
job descriptor datastructure
also touches the question how to represent the job
descriptor datastructure. @Cehteh: I've just pasted
in your preliminary data struct definitinons
from the relevant mailing list discussions.