Repurpose print_queue to be result_queue

It's still very print centric, but it makes it clear
which result items are errors and which aren't.
Return an RC of 1 if any tasks fail
Add part task failures to result queue
Merge branch 'print-queue-repurpose' into develop

* print-queue-repurpose:
  Add part task failures to result queue
  Return an RC of 1 if any tasks fail
  Repurpose print_queue to be result_queue