Completed conversion and cleanup of the Texture class.

	Wrapping mode now uses values defined by the renderer.
	Renamed data members to no longer use m_ prefixes since they are now public.
	Removed DEFAULT_LEVEL_OF_DETAIL and moved it to TextureManager.
TextureManager now has a function to flip textures vertically (thanks to StackOverflow)
Thanks to texture changes, removed unnecessary switches in STB_TextureManager.
Added the repeating flipped wrapping mode from opengl to the texture wrapping options.