Freshening up the repo: updating the sample files and links

[theo-armour]

Looking at the read me, I see that the links point to very early work (http://va3c.github.io/viewer/grasshopper2.html at top of page for example) and there's no indication of the ongoing effort. I would be nice to see a few more links.

Also there are quite a few new sample files in the samples directory, but all are just the .GH files and no JSON files. It would be nice to have more files for testing and building demos...