1. Definition of yyval and d2n added in defs.y (required by latest apple compiler)

2. From bridgebase/Gerardo: skip call to initprogram() if there are 52 cards
   predealt.  (As nothing needs to be don).

3. From BB: -t flag added, program stops after t seconds if no hands are 
   produced. 

4. Removed tmpnam call, use mkstemp instead to avoid warnings on compilation.
