Handle instancing when building the initial shape

[jonathan-meier]

Instancing of a shape in Maya is lightweight shape duplication. Instead of copying the shape geometry for each duplicate, the geometry is simply appended as a child to multiple different transform nodes that position each duplicate (i.e. the shape has multiple parent transform nodes).

Once we use world space vertex coordinates to build the initial shape (Issue #35), we need to think about how we handle instanced Serlio nodes, since the initial shape geometry has multiple world space vertex coordinates (one for each parent transform).

Task:

• Define and implement a strategy for determining the world space vertex coordinates of instanced Serlio nodes.