Plugin loading

@tj.corona How do you feel about a test that dlopens/closes/opens/closes plugin libraries to verify that the crazy ParaView library thing doesn’t cause problems down the road?

It could be helpful, but I think it would be better as a ModelBuilder test (and using ParaView’s library loading routines, not our own). The issues we have encountered thus far would not be caught by a test like this, since they require double registration followed by instantiation of a managed resource described in that library.