entwine .ept format support

[unitycoder]

request for this format:
https://entwine.io/entwine-point-tile.html
https://forum.unity.com/threads/released-point-cloud-viewer-tools.240536/page-13#post-7036813

need to check about it

[unitycoder]

this would require pretty much a separate viewer (not easy to embed into existing viewer..)

so skipping for now, until there is enough market for it.