Improve UV quality

Now there are more pieces been generated during unwrapping but the overall quality is better than before.

thirdparty/simpleuv/simpleuv/uvunwrapper.h

@@ -57,10 +57,10 @@ private:
     std::vector<QRectF> m_chartRects;
     std::vector<int> m_chartSourcePartitions;
     bool m_segmentByNormal = true;
-    float m_segmentDotProductThreshold = 0.00;
+    float m_segmentDotProductThreshold = -0.5;    //120 degrees
     float m_texelSizePerUnit = 1.0;
     float m_resultTextureSize = 0;
-    bool m_segmentPreferMorePieces = false;
+    bool m_segmentPreferMorePieces = true;
 };
 
 }