Add use case #45, Discover Derived Products.  This is part of a renumbering of all of the use cases, and it was previously Use Case #43.
Update the slides with renumbered use cases, and add missing use case scenarios.
Update the provenance use cases, renumbering them into a more logical progression based on functionality. The rename scheme was:

41 was 46
42 -> new (document Script)
43 was 41
44 was 42
45 was 43
46 was 44
47 -> new (Workflow Visualization) (TODO)
48 -> new (Run Visualization) (TODO)