Added init() and shutdown()

Just a proposal for managing initalisation and shutdown of various stuff such as the typedefs of the datacore or libraries that need manual setup (e.g. DevIL in my case, a ton of c-style libraries in general).

I would NOT do such things in the constructor/destructor of the class CGSee, because a class is - by design - not something that can or should be forced to be created only once (...and that's something library-initializers ususally require) and the setup and configuration of some utility-libraries used by other components would just mess up the CGSee class.