DICOM Encapsulation of STL Models for 3D Manufacturing

Adds a new DICOM IOD to encapsulate Stereolithography (STL) 3D model file formats. The new IOD allows 3D manufacturing models to be exchanged between various types of equipment using DICOM.

This adds the ability to store, query and retrieve 3D models as DICOM objects.

Updates are addressed by storing new instances, with reference back to earlier instances.

Line by line review performed. The working group will do a cleanup of the final comments and send the result to the base standard group.