Geometry_Engine: IsPlanar for PolySurface and CompositeGeometry are wrong

[IsakNaslundBh]

Description:

The IsPlanar check for the named methods only check if their subparts are planar, but do not check if they are all co=planar with each other.

Steps to reproduce:

Create a composite geometry/planar surface with multiple planar elements, that are not co-planar with each other.

Expected behaviour:

For method to check if all of the inner objects are co-planar, rather than if the individual elements are planar.

Test file(s):