Typecast levels to array

Signed-off-by: Dries Vints <dries.vints@gmail.com>
Add unit tests

Signed-off-by: Dries Vints <dries.vints@gmail.com>
Cleanup tests

Signed-off-by: Dries Vints <dries.vints@gmail.com>
Use Prologue Support's MessageBag class as base class. Fixes #2

Signed-off-by: Dries Vints <dries.vints@gmail.com>