New graph type which identifies "recreatable" graphs

[trueg]

Currently we put all data in nrl:InstanceBase graphs which is fine. However, we have at least two different types of instance base graphs:

1. data created from desktop resources that can be recreated. This includes data extracted from files and pim items.

2. data created by user interaction. This cannot be recreated.

A new graph type should be introduced to "mark" the graphs that can be recreated. This is important for backup and cleanup tools and probably has many more applications.

Thus, my proposal is to add something like:

nrl:IndexGraph
     a rdfs:Class ;
     rdfs:subClassOf nrl:InstanceBase ;
     rdfs:comment "A graph containing instances that can be recreated by analyzing the original resources." .

[phreedom_]

This is a follow up to #27.

+1 from me with a minor comment fix: "A graph containing triples that can be recreated by analyzing the original resources. Intended to be used by metadata extractors."

Also, how about naming it nrl:DiscardableGraph or something like this?

[trueg]

+1 for the comment improvement.
How about nrl:DiscardableInstanceBase for better readability in combination with nrl:InstanceBase?

[phreedom_]

Agreed. Change committed: r78