Implement all remaining Path issues and use it instead of strings

jedi/api/helpers.py

@@ -44,7 +44,7 @@ def match(string, like_name, fuzzy=False):
 
 def sorted_definitions(defs):
     # Note: `or ''` below is required because `module_path` could be
-    return sorted(defs, key=lambda x: (str(x.module_path) or '',
+    return sorted(defs, key=lambda x: (str(x.module_path or ''),
                                        x.line or 0,
                                        x.column or 0,
                                        x.name))