Merge branch 'sb/rev-parse-show-superproject-root'

From a working tree of a repository, a new option of "rev-parse" lets you ask if the repository is used as a submodule of another project, and where the root level of the working tree of that project (i.e. your superproject) is. * sb/rev-parse-show-superproject-root: rev-parse: add --show-superproject-working-tree