Fix 3D_Viewer

[tferr]

Currently 3D_Viewer is unusable. We need to migrate away from it and adopt ThreeDViewer (see scenerygraphics/sciview#42)

[tferr]

Closing as this is no longer that relevant. Currently, Reconstruction Viewer implements all of this functionality

[ctrueden]

What is "Reconstruction Viewer"?

[tferr]

It is SNT's second and undocommented 3D viewer (The 1st being the legacy IJ1 3D viewer (that we decided not to kill, as some of its functionality is still valid), and the 3rd a-yet-to-be-implemented-bridge to Sciview).
The Reconstruction Viewer is jzy3d-based (thus JOGL), it can (only) render SNT Tree objects (i.e., SWC and TRACES files) and OBJ meshes and It is an "OK viewer" (citing @kephale during an impromptu showcase here at Janelia :)), but because it is aimed exclusively at rendering neuronal morphology data (it was modeled after the MouseLight NeuronBrowser), he have gotten some praise for it by people in the subfield.

The best way to test is to subscribe to the Neuroanatomy update site, and in the Scrpt Editor run Templates>Neuroanatomy>Reconstruction Viewer Demo. Do let us know what you think!

Meanwhile, here is a snapshot: