Update test.bmp

- Found a neat retro bitmap to use in place of the old ugly bitmap I
  found
Enable GNAT switches

- Enable all error checks
- Enable pre/post condition checks
- Enable Ada 2012 mode
Reorganize INIT vars

- Reorganized the SDL_Init parameters
- Removed extraneous SDL_Init option
Change SDL_Rect for new test.bmp

- SDL_Rect Width and Height updated to reflect new test.bmp dims
Flesh out Adventure_Loop

adventure_loop.ads:
- Add pre/post conditions to Adventure_Loop.Start
- Add IsStarted and IsPaused getters to Adventure_Loop

adventure_loops.adb:
- Extend GameLoop with framerate indipendent time logic
  (to be tested)
- Add body to IsStarted