Always use skew-weights instead of our original weighting formula

This dramatically improves our results on skewed meshes, as demonstrated
on one of Sinan's cask setups

framework/include/mesh/FaceInfo.h

@@ -163,7 +163,7 @@ class FaceInfo
   Real neighborVolume() const { return _neighbor_volume; }
 
   /// Return the geometric weighting factor
-  Real gC() const { return _gc; }
+  Real gC() const { return _gc_skewed; }
 
   /// Return the weighting factor for skewed element-pairs
   Real gCSkewed() const { return _gc_skewed; }