made seed time dependent

cpp/full_code/ornstein_uhlenbeck_process.cpp

@@ -54,7 +54,9 @@ ornstein_uhlenbeck_process<rnumber,be>::ornstein_uhlenbeck_process(
 
     for(int thread=0;thread<omp_get_max_threads();thread++)
     {
-            int current_seed = 
+	    assert(omp_get_wtime() != 0);
+            unsigned int current_seed = omp_get_wtime() * 
+                    this->ou_field->clayout->nprocs*omp_get_max_threads() +
                     this->ou_field->clayout->myrank*omp_get_max_threads() +
                     thread;
             gen[thread].seed(current_seed);