Commit.xs: add summary() method
Commit.pm: document summary()
Repository.xs: implement is_shallow(), state() and state_cleanup() methods
Repository.pm: document for is_shallow(), state() and state_cleanup()
Repository.xs: implement new clone options

* remote_name
* checkout_branch
* ignore_cert_errors
* disable_checkout_options
Repository.pm: document new clone options

* remote_name
* checkout_branch
* ignore_cert_errors
* disable_checkout
Changes: update