what is the proper "unplace" to undo
dojo.place( this.format_block('jstpl_stone', {
stone_type:'stone_' + notif.args.color+"_"+this.board_size,
x:notif.args.coord_x,
y:notif.args.coord_y
} ), $( intersection ) );
dojo.place( this.format_block('jstpl_stone', {
stone_type:'stone_' + notif.args.color+"_"+this.board_size,
x:notif.args.coord_x,
y:notif.args.coord_y
} ), $( intersection ) );