RFR: cli: add trees command

[Robin Westberg]

On Fri, 24 Apr 2020 09:23:30 GMT, Erik Helin <ehelin at openjdk.org> wrote:

> Hi all,
> 
> please review this patch that adds
> [trees](https://hg.openjdk.java.net/code-tools/trees) functionality to Skara.
> This is mainly for those who want to use Skara for working with Mercurial today
> and are missing the trees functionality, but I also added a couple of trees
> "commands" like `tstatus`. `tpull` etc. to `skara.gitconfig`.
> 
> Testing:
> - Manual testing of both Mercurial and Git trees commands
> 
> Thanks,
> Erik

Good stuff!

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Marked as reviewed by rwestberg (Reviewer).

PR: https://git.openjdk.java.net/skara/pull/599