Make Module and Bundle properly use empty namespaces

Fix default suggested name of Module instances (now based on desired name
rather than actual assigned name).
Remove parent/child relationship from Namespace.

Previously, Module and Bundle namespaces were "children" of the Module
definition namespace. This could lead to collisions that would give unexpected
names for module instances or Bundle elements. In particular, otherwise
identical modules that instantiate other identical modules in such a way that
the instance cannot be named via reflection would not be deduplicated because
the names of the instances would collide with the names of the modules in the
Builder.globalNamespace.