Update and add image of ST_CompactnessRatio
Update ST_CompactnessRatio
Update doc and image of ST_CompactnessRatio
Correction ST_CompactnessRatio
Update ST_CompactnessRatio
Update link to ST_CompcatnessRatio
Improve explanation
Merge branch '138' into gh-pages

Update and add image of ST_CompactnessRatio