feature work for supporting multiple inputs
- added some more error checking
- when the mesh is unplugged from the compound array attribute, it deletes that array entry (however, the output is still cached in the mesh node)
- fixed a bug with inputComponents for faces
- switched inputComponent type edge from edge iterator to calls to MFnMesh::getEdgeVertices
Refactored for ease of maintenance.
- created DDConvexHullNode::processInputIndex to process each index of the input array attribute and append to the list of allPoints
- added function to DDConvexHullUtils to convert a single indexed component to vertex IDs.  Currently only vertices, faces, edges, and face verts are supported.