Updated OpenMP warning to use the PyClaw logging. This prints to the …

…console and to the log file.

src/pyclaw/classic/solver.py

@@ -610,15 +610,17 @@ def __init__(self, riemann_solver=None, claw_package=None):
         self.aux2 = None
         self.aux3 = None
         self.work = None
+        self.nthreads = None
+
+        super(ClawSolver3D,self).__init__(riemann_solver, claw_package)
 
         import os
-        import warnings
         if 'OMP_NUM_THREADS' not in os.environ:
-            warnings.warn("The environment variable 'OMP_NUM_THREADS' is unset.  Set this variable to use OpenMP with more than 1 thread (i.e. export OMP_NUM_THREADS=4).")
+            self.logger.warn(""""The env variable 'OMP_NUM_THREADS' is unset.
+                                       Set this variable to use OpenMP with more 
+                                       than 1 thread (i.e. export OMP_NUM_THREADS=4).""")
         self.nthreads = int(os.environ.get('OMP_NUM_THREADS',1))
 
-        super(ClawSolver3D,self).__init__(riemann_solver, claw_package)
-
     # ========== Setup routine =============================   
     def _allocate_workspace(self,solution):
         r"""