Add ability to clone a repo

[billygriffin]

Describe the feature or problem you’d like to solve

I want a simpler way to clone a repo than having to remember or copy the syntax for a git clone from github.com.

Proposed solution

I want to be able to clone a repo quickly and easily with either owner/repo or URL.

gh repo clone [repo]

[nightpool]

after PR check out, this is my second most used hub command, so I would love to see it in gh!

[joshuabezaleel]

I guess the way we could do this is by using the REST API's Get contents_url and traverse it recursively for each of the folder's files' download_url?

[jasonkarns]

Noting this in advance for whenever development begins on this feature: I would love if the owner portion of the owner/repo string could be set via git configuration.

I heavily leverage git's Conditional Includes coupled with a directory structure hierarchy that replicates repo ownership. (ie: ~/code/org-a/repo1, ~/code/org-a/repo2, ~/code/org-b/repo) This gives me the ability to apply configuration to git that is contextually aware of the org and unique to the given org (or owner).

Extrapolating, if gh respected a git configuration of, say: git config gh.owner, then one could set the owner according to the directory. This would enable, say cd ~/code/acme; gh clone anvil instead of gh clone acme/anvil. (This becomes more useful given a non-trivial org-name or if running a multitude of commands that require the --repo flag.)