Do EFC for the first faded layers of SLA, interpolate efc parameters

Compensated slices have negative orientation...


Move efc to common params


Fix elefant foot compensation reversed contours


Remove redundant assertions and don't apply absolute correction if zero

src/libslic3r/SLAPrint.hpp

@@ -152,6 +152,10 @@ public:
         }
 
         const ExPolygons& get_slice(SliceOrigin o) const;
+        size_t            get_slice_idx(SliceOrigin o) const
+        {
+            return o == soModel ? m_model_slices_idx : m_support_slices_idx;
+        }
     };
 
 private: