One less magic number in OvaryPowerThreshold

1.3/source/RJW_Menstruation/RJW_Menstruation/HediffComps/HediffComp_Menstruation.cs

@@ -139,7 +139,6 @@ namespace RJW_Menstruation
             get
             {
                 if (opcache >= 0) return opcache;
-                // Climacteric will set in 6 (human) years before egg exhaustion
                 float avglittersize;
                 try
                 {
@@ -150,9 +149,10 @@ namespace RJW_Menstruation
                     // Any exceptions in that will have been reported elsewhere in the code by now
                     avglittersize = 1.0f;
                 };
+                const float yearsBeforeMenopause = 6.0f;
                 opcache = (int)(RaceCyclesPerYear() *
                     avglittersize *
-                    6f *
+                    yearsBeforeMenopause *
                     (Pawn.def.race.lifeExpectancy / ThingDefOf.Human.race.lifeExpectancy));
                 return opcache;
             }