Changed structure. Added 1-level subclassing

Changed structure to allow class configs in-folder. Moved all existing
classes/* files into includes, replacing them with the classes for all
of the different classes.

Added 1-level subclassing to the class system. (Intended purpose is for
player class configs to subclass generic class which provides the
required methods. Also later will have a generic module interface, and
then EH modules will subclass the generic module class)