0030394: Modeling Algorithms - Empty result of offset operation (mode "Complete"...

0030394: Modeling Algorithms - Empty result of offset operation (mode "Complete", join type - "Intersection")

The following changes have been made for improving the offset algorithm:
1. Multi-connexity support - intersection of the faces connected to the edge belonging to more than two faces is now performed.
2. Avoid intersection of the faces connected through internal edge.
3. Filling gaps (holes) in the splits of the created offset faces to increase possibility of creation of the closed volume from these splits.

Test cases for the issue.