Remove PathGroups for Groups.

[asturur]

close #1520

The only point of PathGroups was handling a svg import and handling the transformMatrix over the objects.

Pathgroups were mostly groups but without sub targeting and without the ability to go more deep with nesting.

TransformMatrix math has been solved hand now ti can be absorbed in normal groups.

So path groups are really no more necessary.

• fix last failing UT
• fix all import tests ( gradients are broken )
• give group a way to choose center and width/height to simulate svg clip

[saurabhudaniya200]

in which version this was added?

[asturur]

This was a breaking change for 2.0