Created the ResourceManager, Resource, and TextureResource classes.
The ResourceManager provides a unified interface for accessing resource
data, embedded or from the filesystem, with
initialization/deinitialization handled automatically behind the scenes.
It also keeps from creating duplicate resources (e.g. when two
ImageComponents use the same image file).
Audio still needs to be moved over to it.
Merge branch 'master' into unstable
Merge branch 'master' into unstable
Merge branch 'master' into unstable

Conflicts:
	src/components/ImageComponent.h
Moved Fonts to be Resources.
Moved Renderer::drawText stuff to the Font class.
Fonts are now used as std::shared_ptrs.
Fixed memory leak in ImageIO.cpp
Remove debug messages
Merge branch 'master' into unstable
Moved to class-individualized static gets for resources.
See issue #95 for discussion.
Initialize mOpacity.
ResourceManager stores Reloadables in a list, instead of vector.
Fix GuiGameList list positioning.