Clean up druid-shell info and add new info to Cargo.toml.

[xStrom]

Cargo.toml still contained a bunch of druid-shell info that hadn't been changed since forking. This PR addresses that.

I also added better example scraping for docs, which is ported over from the latest druid-shell.

[DJMcNab]

I want to check that we actually use the image crate at all. I had been intending to just remove the giant stack of random features.

Alternatively, could we use image = * or equivalent to just use whatever version of the image crate is in the binary, and then not re-export?

[xStrom]

Worth checking indeed. I think in Druid druid-shell just re-exported it and didn't use it itself.

[xStrom]

I confirmed that image isn't used at all and neither was im, so I removed these completely.