SDL interface created.

Add class SdlInterface - SDL library interface.
Add class Sdl - implementation of SdlInterface.
Add class SdlMock - mock class for testing.

Update N/A.

Fix N/A.
Application is running.

Add class ApplicationInterface - application class interface.
Add class Application - implementation of ApplicationInterface.
Add class ApplicationMock - mock class for testing.

Update N/A.

Fix N/A.