Implement exporting to Neuroglancer formats

[sanjayankur31]

https://github.com/google/neuroglancer looks very good. Here are some examples: https://h01-release.storage.googleapis.com/gallery.html

It'll be good if we can export to neuroglancer supported formats and setup a way to allow users to use neuroglancer to view models.

[spanag]

At a glance it's not clear how triangular meshes are supported in practice. This may help: https://github.com/seung-lab/cloud-volume
This issue and linked ones look related, they are about SWC but diameter is not implemented: google/neuroglancer#169

If "render-tight" meshes are needed (no visible gaps), dev Eden can generate them.
If a voxel volume is preferable, triangle count is not a concern, and especially if it should look somewhat natural, this work may help if accessible: https://doi.org/10.1016/j.jneumeth.2013.09.011 (may be the same as in Neuron rxd).