Clean up entry point module

Now correctly references http://ankisrs.net/, removes spelling error,
and cleans up whitespace to conform to Python standards.
Improve ease of use for config module

Augments the Config class such that

- the __name__ attribute is set, allowing help() calls on methods, and
- __getattr__ is defined, allowing the former config.xxx style to work.
Allow replacing existing tags in mass generator

Adjusts the checkbox on this screen to be reworded according to whether
in overwrite or append mode. Now, in append mode, the user is given the
option of whether or not to remove existing sound tags from the
destination field.