Log Message:
Changes 1.3.6:
 * different color palette used by default
 * PNG screenshots added
 * added sector counter and speedometer
 * F6 is Atari HELP key on Curses, Falcon and in X11
 * added missing combinations of ANTIC modes with GTIA modes
 * keyboard joystick works in more games (doesn't pause the game) in SDL
 * mouse joystick emulation works in X11
 * cassette loading by hardware registers (Ninja and Elektraglide
   are examples of games that load correctly now)
 * blank boot ATR disk image can be created in the Disk Management menu
 * many small fixes and major source code clean up