Bugfix in normalize_module_name

Previous code looked for the patterns 'module.' and '.module' separately
and removed the first instance.
Issues with this:
* Too broad. If a user gives some module a name that has the prefix or
  suffix 'module', that pre/suffix would be removed.
* Doesn't catch the corner case of the "root" module in a model

Modified to split name by the module separator '.', and then remove the
first instance of the name 'module'