The TemplateLoaderMixin class is a simplistic loader which performs no caching.
os.path.join()
on the base_dir specified in the
constructor and the name argument.
If there is an error reading the template a ApplicationError will be raised.
The class remembers the names of all loaded templates.
None
if the template specified in the name
argument has been previously loaded. If not previously loaded it is
loaded via the load_template() method and returned.