Added EH_CoreModules. Changed way to register module

Added EH_CoreModules addon folder which will contain all of the modules
that have core functionality.

Finalized the method to register a new module. Now pass in module_name,
and get back a class you can mess with. All modules are initalized one
at a time on PLAYER_LOGIN automatically. Module author only has to
override the default methods of the Module class if needed.