Removed the multipole order constant definition from const.h

src/const.h

@@ -39,9 +39,6 @@
 /* Thermal energy per unit mass used as a constant for the isothermal EoS */
 #define const_isothermal_internal_energy 20.2615290634f
 
-/* Self gravity stuff. */
-#define const_gravity_multipole_order 1
-
 /* Type of gradients to use (GIZMO_SPH only) */
 /* If no option is chosen, no gradients are used (first order scheme) */
 //#define GRADIENTS_SPH

src/gravity_derivatives.h

@@ -23,7 +23,7 @@
  * @file gravity_derivatives.h
  * @brief Derivatives (up to 3rd order) of the gravitational potential.
  *
- * We use the notation of Dehnen, Computational Astrophysics and Cosmology, 
+ * We use the notation of Dehnen, Computational Astrophysics and Cosmology,
  * 1, 1, pp. 24 (2014), arXiv:1405.2255
  */