Resolve "Emplace API inconsistent with ProcessorTrackerFeature/Landmark functions"

Closes #191 (closed)

include/core/factor/factor_autodiff_distance_3D.h

@@ -34,7 +34,6 @@ class FactorAutodiffDistance3D : public FactorAutodiff<FactorAutodiffDistance3D,
                             _feat->getFrame()->getP(),
                             _frm_other->getP())
         {
-            setFeature(_feat);
         }
 
         virtual ~FactorAutodiffDistance3D() { /* nothing */ }