Testing dev branch commit
Added string constants for system identifiers
Added a message system identifier

#1
Added file stubs for #1

Added Message_Handler, Resource_Handler, Game_Manager, and Base System
stubs
Added stubs for #1
Updated file header comment
Added screen class and added to the game manager
Began implementing cGame_Manager methods
#1 Continued implemented cSystem, cGame_Manager, and cMessage_Handler
#1 Finished implemeting basic system structure

Implementation is complete to allow the following:
    Creation of new user entities through a factory
    Manual creation of entities including addition of components
    Creation and registration of a base system with the game manager
    Registering of entities with the game manager which also registers
entity with each registered system including a requirements check on
the system
    Added a game logic update section the performs an update method on
the base system each game tick
Merge pull request #8 from n8ebel/development

Development