SE3 rotation_curve and translation_curve methods are now const

include/curves/se3_curve.h

@@ -216,9 +216,9 @@ struct SE3Curve : public curve_abc<Time, Numeric, Safe, Eigen::Transform<Numeric
   /// \return \f$degree\f$, the degree of the curve.
   virtual std::size_t degree() const { return translation_curve_->degree(); }
   /// \brief const accessor to the translation curve
-  const curve_ptr_t translation_curve(){return translation_curve_;}
+  const curve_ptr_t translation_curve() const {return translation_curve_;}
   /// \brief const accessor to the rotation curve
-  const curve_rotation_ptr_t rotation_curve(){return rotation_curve_;}
+  const curve_rotation_ptr_t rotation_curve() const {return rotation_curve_;}
   /*Helpers*/
 
   /*Attributes*/