Updated documentation for ResourceManager #45
Added new ResourceManager stub

Added a new ResourceManager class to develop the new resource manager
without breaking current functionality

Added code to Game to store the path of the application
Worked towards implementing new resource manager

Worked on design document for ResourceManager section

Implemented a simple XML parsing test to lay the groundwork for
implementing a game config file
Incorporated tinyxml2 into project to read Config file
Implemented basic reading of resource elements from Resources.xml
Implemented input handling from current state

Added Command base class, and PopStateCommand
Added methods to register commands with key actions

Key actions are registered from OnResume of a state
Added a PushState command

Started initial implementation of a PushStateCommand class
Allows user to push a new state onto a stack
Finished implementing PushStateCommand
#47 Current state now pauses when new one is pushed
#45 #49 Added base Resource class

Added an abstract base Resource class
This will be extended to handle audio and drawable resources

Comment out some parts of the current ResourceManager implementation
that will be rewritten to reflect the updated Resources design
#49 Implemented basic Sprite class for images
Implemented boilerplate Audio class

Audio class will wrap SDL audio types and functionality
Playing audio will be done by AudioService so it is a friend class

Moved header includes for SDL2_image and SDL2_mixer to Resource.h
Began modifying ResourceManager interface

Began modifying the ResourceManager interface to incorporate Sprite,
Audio, Font objects

Added methods for loading a sprite, audio, or font
Changed method name of LoadImage to LoadOptimizedImage

LoadOptimizedImage will then be used by LoadSprite to get the optimized
image surface to store in the Sprite object
Updated Sprite interface to match current standards

Changed method names to match the format used in all other classes

Modified one getter method of Window to be const
#49 Finished implementation of basic sprite loading

Sprites defined in Resources.xml will be loaded as Sprite objects if
they the image can be loaded and optimized correctly

If the image belonging to a sprite can’t be loaded or optimized, no
Sprite resource is created

It is up to the user to check if a returned Resource* from
ResourceManager.GetResource() returns a valid resource or not
#53 Implemented SoundEffect class and loading

Added a SoundEffect class to wrap Mix_Chunk
Implemented the loading of SoundEffect objects from the Resources.xml
file
Added a <SoundEffect> tag for Resources.xml file to indicate
SoundEffect objects to load

Added SDL_mixer and SDL_image initialization in Game.Init()
#53 Replaced Audio class with SoundEffect class
#52 Added Music class to wrap SDL Mix_Music
#50 Implemented Font class and font loading

Added a Font class to wrap SDL TTF_Font
Added xml tags for Resources.xml
Added oxygen documentation