Fixed error in computation of inverse conditioning

git-svn-id: https://geuz.org/svn/gmsh/trunk@19607 59c8cabf-10d6-4a28-b43f-3936b85956c4
Added inverse conditioning to mesh quality optimizer

git-svn-id: https://geuz.org/svn/gmsh/trunk@19608 59c8cabf-10d6-4a28-b43f-3936b85956c4