3D viewer cannot load larger detailed models

まだ誰も着手していません。

It looks the 3D viewer fails with larger models.

I have a model here with 10 detailed human cells. The model will load, and one can use the various controls, but the 3D viewer remains blank.
If I reduce the model to 8 cells, the 3D viewer loads.

So, we need to:

- optimize the geppetto model conversion to allow the 3d viewer to show larger models: come up with some ways to simplify the morphology if there are too many segments etc.
- when the model is too large and it cannot be shown in the 3d viewer, **we need to inform the user and not silently fail**

Data:
- Model that can be visualized: with 8 cells, no biophysics, : [HL23Net_0.001.net.nml.zip](https://github.com/MetaCell/NetPyNE-UI/files/12040175/HL23Net_0.001.net.nml.zip)
- Model that cannot be visualized: with 12 cells, no biophysics:
[HL23Net_0.001-12cells.net.nml.zip](https://github.com/MetaCell/NetPyNE-UI/files/12040350/HL23Net_0.001-12cells.net.nml.zip)

まず、添付された8セルモデルと12セルモデルを3Dビューアーに読み込み、レンダリング結果が空白のままになる場合のモデル変換パスを追跡します。より大きく詳細なモデルが正常にレンダリングされるか、モデルを表示できない場合にビューアーがサイレントに失敗するのではなく、そのことをユーザーに明確に知らせれば完了です。

索引モデルが issue の本文から書いたものです。