Volume interaction

Generating volume elements on a mesh is done with a specific Interaction called FieldApplicator:

app = FieldApplicator(no)
app.push(gObject1)
app.push(gObject2)
...
app.addProperty(prp)        # association of an ElementProperties
app.addRuptureCriterion(rc) # failure criterion (optional)
interactionset.add(app)     # the interaction is added in InteractionSet

or

app = interactionset.add(FieldApplicator(no)) #add returns a reference
app.push(gObject1)
app.push(gObject2)
...
app.addProperty(prp)        # association of an ElementProperties
app.addRuptureCriterion(rc) # failure criterion (optional)

where

`no`	number of the `Interaction` (which is to say the `FieldApplicator`)
`gObject1`	mesh geometric entity where the finite elements are applied
`prp`	Properties of volume elements to generate.
`rc`	optional Failure criterion