Rewrite/api

[chariskar]

Rewrite the api package of breakthemod to ease the development experience.

Major changes:

• Migrate to a composition based design for Base* classes.
• Introduce BaseWidget and WidgetConfig for widgets.
• Change the design of BaseCommand and BaseModule so that name, description and usage suffix/hidden are set by constructor parameters instead of being values that get overriden.
• Change NearbyHud to NearbyWidget and to use the new BaseWidget class.
• Change the player cache to be a HashMap with the names of the users as strings.
• Change the town and nation caches to only store the names.