new EMF+ Parser: Implementation of fillPolygon

This implementation replaces hte old one.
It uses the workaround hatch blending from the old implentation (basically just copied)
It provides correct linear gradients, with correct transformations
PathGradients are approximated via RadialGradients.
Also, there is a better line width choice, solving problems caused by pictures like tdf#38580.

Change-Id: Ida4f36a5de83b6325702a153b642abe5e45982ee
Reviewed-on: https://gerrit.libreoffice.org/40831Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Bartosz Kosiorek <gang65@poczta.onet.pl>