Add procedure for creating a generic collection of items to be added to neurons (e.g. mitochondria)

[nneubarth]

Procedure would create a node (e.g. MitochondrionSet) similar to SynapseSet, which would point to all of the items (e.g. Mitochondrion) in the collection.

[nneubarth]

The deleteNeuron procedure needs to be aware that these collections exist, so that the collection is deleted when a neuron/segment is deleted. It could be potentially dangerous if these collection nodes and item nodes used labels that are already existing in the database since many of these labels are used for other procedures, and users may be using these labels in their analysis, so e.g. even if the items were synapses I would label them with something like :Synapse2.

Another idea: instead of allowing a user to use any label, use the same label for all of them and have a property that specifies the type of collection. E.g. :Collection nodes contain :Item nodes and these nodes have a "type" property that can be equal to say, "mitochondria"

stub:

neuPrint/neuprint-procedures/src/main/java/org/janelia/flyem/neuprintprocedures/proofreading/ProofreaderProcedures.java

Line 1328 in 67e4f68

@Procedure(value = "proofreader.addGenericCollectionToSegment", mode = Mode.WRITE)