largefiles: align the output messages for an added file with core methods
Core addremove prints the file relative to cwd only if patterns are provided to
the command. Core add always prints relative to cwd. Also, both methods print
the subrepo prefix when needed. The 'already a largefile' doesn't have an
analog in core, but follows the same rules for consistency.
.. Common link and substitution definitions.
.. |hg(1)| replace:: **hg**\ (1)
.. _hg(1): hg.1.html
.. |hgrc(5)| replace:: **hgrc**\ (5)
.. _hgrc(5): hgrc.5.html
.. |hgignore(5)| replace:: **hgignore**\ (5)
.. _hgignore(5): hgignore.5.html