adopting the qcproperties script to be able to qc by polygons

[miroine]

When performing a qcproperties in a model, filtering by a polygon is quite needed in order to visualize the different statistics in this area, currently the #xtgeo has a capability of creating a discrete region from a polygon ... but if we have different polygons that intersect each others (example: looking at a possible area statistcs for a possible target, with different size of that region, if we want to represent that by a 3D regions than the number of discrete region might be quite important) .... that s why a #feature_request to filter by polygons would be more appropriate