Update of game pages

The behaviour of the game pages has changed a little: you can repeatedly preview your moves - and start afresh with the new "New Move" button.

Furthermore I split up the links so that the more important action links stay close to the chess board. The help links might still be pushed down by the "move dialogue" (the move and messages entry form on the right), if it shows a lot of text.

Please note that the version of the updated game pages is 4.02.