doc/common.txt

phase: alway return a value

With the previous code, the phase command was returning None when displaying
phase and 0 or 1 when moving them.

This seemed an bit odd and displaying phase return 0 too now.

.. 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