Deprecate Branch.Checkout()

[nulltoken]

As discussed in #840 (comment)

branch.Checkout() modifies the external state (workdir, index and potentially the HEAD state). It may make sense to deprecate it in favor of IRepository.Checkout()

Thoughts?

[carlosmn]

Makes sense, as the checkout isn't an operation on a branch, but an operation on the repository/workdir. The branch is the argument which tells it what to use.

[bording]

Looks like this issue can be closed since commits 19cd9f5 and aa70916 took care of this already!

[nulltoken]

Thanks!