Add helper_functions include for inverse and in general header

matrix/SquareMatrix.hpp

@@ -15,6 +15,7 @@
 #include <math.h>
 
 #include "math.hpp"
+#include "helper_functions.hpp"
 
 namespace matrix
 {

matrix/math.hpp

@@ -13,3 +13,4 @@
 #include "Scalar.hpp"
 #include "Quaternion.hpp"
 #include "AxisAngle.hpp"
+#include "helper_functions.hpp"