Animations and image loader

Cleaned up pull request:

* Added animation classes

* Added image loader utilizing DevIL and removed SDL_image

I decided to use DevIL instead of libpng/libjpeg because:

* longjmp apparently doesn't work on Windows (or I can't get it to work - if it is possible, it could be added in the future)

* It's much smaller than SDL_image and doesn't depend on SDL (core)

* It's already available in the Derelict repository in DQuick