Improve Forking and Saving

[Gaurav0]

1. The fork menu option now no longer appears unless you do not own the gist
2. The save option forks if you do not own the gist

Relevant to issue #153

[stefanpenner]

SGTM –

[chancancode]

Can we add back a way to fork your own twiddle? I find myself wanting to do it quite often for various reasons: creating stable "steps" I can embed in a long tutorial, having a base template to build off of, etc. I would even take something like "hold down option key to change save to fork" :) (But I think it is still quite legitimate that you would want to fork your own twiddle, so I don't think it needs to be a hidden/advanced feature)

Also, I have a UI suggestion along the same lines: The file menu currently mixes commands that operates on file-level (add/move/delete) vs things that operates on the twiddle level (new/save/fork/share). Maybe move the latter above the divider to separate the two sets of things?

(Actually, it's already supposed to work that way: there is a bug though, when you are not authenticated, it doesn't show the divider)

[Gaurav0]

The github api does not provide a way to fork one's own gist, it just returns an error if you try to do so. An issue is open for duplicating one's own gist, but it will likely be a copy, not a fork with a link to the original or ability to PR.

[chancancode]

👍 that actually works well for my purpose, thanks!