Manager is responsible for processing Database, loading Language Data and changing active language at runtime.
You can define your own Manager by creating a class that implements IKnotManager or deriving from KnotManager. After that you are able to select it in Project Settings.
Note
Custom class should have no constructor or at least one public constructor without arguments.
Warning
If you decide to remove, change the name, namespace or assembly of custom class you will get serialization error and possibly lose data. As a temporary solution, add [MovedFrom] attribute to your class before making those changes.