Adding base class for NeumannFuncObj so that classes that cache
pointers to these objects can cache a non-templated base class.
NeumannFuncObj now a subclass.
NBCContainer now works with NeumannFuncObjBase
BCHandlingBase starting to work with NeumannFuncObjBase.
Checkpointing some work on updating output types from NeumannFuncObj
in the BoundaryConditions methods.