Materials should present their own plots for material viewer

[hughesadam87]

Currently, plot selector is recursively looking for IView objects:

def flatten_traitobject(traitobject, *types, **kwargs):
    """ Flatten a trait object, return dictionary.  Use ignore keyword
    to pass over trait names that might cause recursion errors.  For example,
    the mview trait has a reference back to model.  This will cause recursion 
    loop between Material and Mview, so ignore it.
    """
    node_map = {}
    node_path = [] 
    ignore = kwargs.pop('ignore', [])
    def nodeRecursiveMap(traitobject, node_path): 
        for key in traitobject.editable_traits():
            val = traitobject.get(key)[key]
            for type in types:
                if isinstance(val, types[0]):
                    node_map['.'.join(node_path + [key])] = val 
            try:

                print traitobject, key
                if key not in ignore:
                    nodeRecursiveMap(val, node_path + [key])
            except (AttributeError, TypeError):
                pass
    nodeRecursiveMap(traitobject, node_path)
    return node_map

This is slow and also falling into recursion errors. Would be faster, and less error prone for materials themselves to offer an organized layout of their view. For basic materials, something like:

'materail': mview

But for composite mateiral

'material1': Material1.mview 'material2': Material2.mview

Then for nanomaterials, can customize in alphabetical order (SHOULD BE ORDERED DICT)

'corematerial':... 'mie thoery':...

Then if all materials have this, plot selector can easily call something on the selected_layer.material. EG selected_layer.material.viewdict()