Handle a <param name="game_id"> by passing it in to the C side as

argv[1], which in turn feeds it into the midend as a game ID. This
can of course take any of the forms supported by the native C
puzzles: a pure game parameter string, a params:description specific
game ID, or a params#seed random game ID.

git-svn-id: svn://svn.tartarus.org/sgt/puzzles@8095 cda61777-01e9-0310-a592-d414129be87e