Feature suggestion: Easy copy/paste support for images

[eugene-shvarts]

I'd love to be able to copy an image from elsewhere, and while the app's open to Image-to-Image, just paste to input it.

Likewise, for any of the image outputs, I'd love to either copy the image automatically when I hit cmd+C while an output is shown, or when I click the image and have the full-size image window active, or for either, be able to right click the image and copy it that way.

[eugene-shvarts]

While on the topic of easier keyboard navigation, Cmd+Enter to hit Generate (or whichever button is default/in blue) would be great too.

[Leland]

be able to right click the image and copy it that way

Is coming in #150