fixes #224 : use the Envelope to calculate the centroid
fixes #224 : use the Envelope to calculate the centroid
Merge branch 'bug/224-wrong-centroid-when-preview-geom-has-a-hole' of github.com:cismet/cids-custom-wuppertal into bug/224-wrong-centroid-when-preview-geom-has-a-hole
Merge branch 'bug/224-wrong-centroid-when-preview-geom-has-a-hole' into dev