Let unshelve continue after errors.
Refactor.
Update docs.
unshelve --force ignores errors while `Get`ing files.
Make the unshelve --force warnings shorter.
Merge pull request #636 from spraints/ignore-unshelve-errors

Add the option to ignore unshelve errors
Method GetChangesets() only for tfs2008 to avoid bad changesets returned when getting by lots

Expected fix #642
Try without the Retry.Do()
Correct the double fetch of changesets
Directly as if "Is2008OrOlder"
Merge pull request #646 from pmiossec/fix_wrong_changesets_order_tfs2008

Method GetChangesets() only for tfs2008 to avoid bad changesets returned...
Use libgit2sharp to find commits to checkin
Adapt FindParentCommits() to return nothing when commits are not parents
Unit test