ENH: use combined &=, |=, ^= forms for bitAndEqOp, bitOrEqOp, bitXorEqOp

- these also work for bitSet, HashSet with slightly lower overhead

ENH: locate FOAM_NODISCARD attribute macro in stdFoam.H

applications/test/scalarOps/Test-scalarOps.C

@@ -126,6 +126,9 @@ int main(int argc, char *argv[])
     testDivide<vector>(vectors);
 
 
+    //(void) compareOp<vector>()(vector::zero, vector::one);
+
+
     Info<< "\nEnd\n" << endl;
 
     return 0;