Classic "Snake" game

Object of game is to see how long you can grow the snake.
Use arrow keys to control direction of snake.
Hold SHIFT key to move faster.
Hit flashing target to grow snake by one segment.
Hitting wall, self or blocker will end game.
Game gets harder as snake becomes longer and longer.
Press ESCAPE to quit.

Command line options:
  L=0 to 75     <= Set initial length of snake body (default 10)
  B=n           <= Place 'n' blockers in playing field (default 0)
