find/replace pi/180.0 -> degToRad() and 180.0/pi -> radToDeg()

- note left utilities/mesh/advanced/collapseEdges/collapseEdges.C as-is.
  It looks suspicious, but the change was recent, so maybe it means something

tutorials/compressible/rhoCentralFoam/biconic25-55Run35/datToFoam/datToFoam.C

@@ -128,7 +128,7 @@ int main(int argc, char *argv[])
     fileName pointsFile(runTime.constantPath()/"points.tmp");
     OFstream pFile(pointsFile);
 
-    scalar a(0.1*constant::mathematical::pi/180.0);
+    scalar a(degToRad(0.1));
     tensor rotateZ =
         tensor
         (