A few minor things to improve efficiency for intersection calcs

Refs #10169

Code/Mantid/Framework/Geometry/inc/MantidGeometry/Surfaces/Plane.h

@@ -82,7 +82,7 @@ namespace Mantid
       double distance(const Kernel::V3D&) const;      ///< distance from a point
 
       double getDistance() const { return Dist; }  ///< Distance from origin
-      Kernel::V3D getNormal() const { return NormV; }    ///< Normal to plane (+ve surface)
+      const Kernel::V3D & getNormal() const { return NormV; }    ///< Normal to plane (+ve surface)
 
       void rotate(const Kernel::Matrix<double>&);
       void displace(const Kernel::V3D&);

Code/Mantid/Framework/Geometry/src/Objects/RuleItems.cpp

@@ -292,9 +292,11 @@ Intersection::isValid(const Kernel::V3D& Vec) const
     @retval 0 :: Vec is outside object.
   */
 {
-  if (!A || !B)
-    return false;
-  return (A->isValid(Vec) && B->isValid(Vec)) ? true : false;
+  if(A && B)
+  {
+    return (A->isValid(Vec) && B->isValid(Vec));
+  }
+  return false;
 }
 
 bool
@@ -849,9 +851,10 @@ SurfPoint::isValid(const Kernel::V3D& Pt) const
   */
 {
   if (key)
-    return (key->side(Pt)*sign)>=0 ? true : false;
-  else
-    return false;
+  {
+    return (key->side(Pt)*sign)>=0;
+  }
+  return false;
 }
 
 bool 

Code/Mantid/Framework/Geometry/src/Surfaces/Plane.cpp

@@ -220,8 +220,7 @@ Plane::side(const Kernel::V3D& A) const
     @retval 0 :: A is on the plane itself (within tolerence) 
   */
 {
-  double Dp=NormV.scalar_prod(A);
-  Dp-=Dist;
+  double Dp=NormV.scalar_prod(A)-Dist;
   if (Tolerance<fabs(Dp))
     return (Dp>0) ? 1 : -1;
   return 0;