Some improvements on exception handling

• Let Mooney Rivlin throw Dune::MathError instead of generic exception.
• Directly re-throw an exception in the ADOL-C assembler to avoid changing the type.

dune/elasticity/assemblers/localadolcstiffness.hh

@@ -77,7 +77,7 @@ energy(const LocalView& localView,
         energy = localEnergy_->energy(localView,localAConfiguration);
     } catch (Dune::Exception &e) {
         trace_off();
-        throw e;
+        throw;
     }
 
     energy >>= pureEnergy;