Changed access to Matrix44 data

Author: cpr-mab

src/DataTypes/Matrix44.h

@@ -140,7 +140,7 @@ class Matrix44 {
    */
   robotcontrolapp::Matrix44 ToGrpc() const;
 
-private:
+protected:
   // Contains the matrix data
   std::array<double, 16> m_data;
 };