SFML2 Renderer

New SFML2 renderer with a VertexBuffer object, speed is on par with the DX/OpenGL renderers. Also fixes the clipping problems with the original SFML 1.6 version and the window is fully sizeable.

Other changes:
Cleaned the old SFML renderer/sample from SFML 2 code.
Fixed build scripts on Linux (still need to identify what libraries exist on system)