Fallback describes the mechanism, while unspecified explains what the
user is thinking.

This describes their purpose better, as we now initialize ssl and some
other global stuff in there. Calling the init function is not something
which has been optional for a while now.

This allows you to use a --repeat option to run status over and
over and see how the output changes as you make local directory
changes without reopening the git_repository object each time.

Also, adds a flag to explicitly list the submodules before status.

`git_submodule` objects were already refcounted internally in case
the submodule name was different from the path at which it was
stored.  This makes that refcounting externally used as well, so
`git_submodule_lookup` and `git_submodule_add_setup` return an
object that requires a `git_submodule_free` when done.

Relicense examples under CC0

Update the explanation to reflect our use of git_status_list_new() and
make the breaks in rocco more meaningful.

Clarify why GIT_STATUS_CURRENT and index_to_workdir don't always imply
each other. Fixes #1740.