GlobalNamespace doesn't use a lot of attributes - remove them

jedi/imports.py

@@ -41,18 +41,8 @@ class ImportPath(pr.Base):
     """
     class _GlobalNamespace(object):
         def __init__(self):
-            self.start_pos = 0, 0
             self.line_offset = 0
 
-        def get_defined_names(self):
-            return []
-
-        def get_imports(self):
-            return []
-
-        def get_parent_until(self):
-            return None
-
     GlobalNamespace = _GlobalNamespace()
 
     def __init__(self, import_stmt, is_like_search=False, kill_count=0,