SDL graphics/game tutorial, 9 new chapters

Finally got “part d” of my graphics/game tutorial ready - about 8000
words in nine new chapters (not counting the code snippets), covering
things like:

  • integration of the new effects to the game
  • moving camera
  • larger levels
  • collisions with walls
  • a better physics model
  • game states and transitions

The whole tutorial .html files weight at about 480kB now. Phew.