fixed bug in colormap when not normalizing

Former-commit-id: a6eb82a7896d97f653b1863291de75cf86a5aecf

include/igl/colormap.cpp

@@ -1378,7 +1378,7 @@ IGL_INLINE void igl::colormap(
   Eigen::PlainObjectBase<DerivedC> & C)
 {
   const double min_z = normalize ? Z.minCoeff() : 0;
-  const double max_z = normalize ? Z.maxCoeff() : -1;
+  const double max_z = normalize ? Z.maxCoeff() : 1;
   return colormap(cm, Z, min_z, max_z, C);
 }