Urgency

- Added a coefficient for ageing which is the increase (or decrease)
   of urgency per day. The calculated urgency offset due to ageing
   can be limited by setting urgency.age.max.

src/Task.h

@@ -117,6 +117,7 @@ private:
   inline float urgency_next () const;
   inline float urgency_due () const;
   inline float urgency_blocking () const;
+  inline float urgency_age (float, float) const;
 };
 
 #endif