VMM/cli: w_err() call os.sys.exit only if code != 0.
read_pass() write errors to stderr. And a few other small fixes.
.. set references to other manpages and set links in the html output
.. |vmm(1)| replace:: **vmm**\(1)
.. _vmm(1): vmm.1
.. |vmm.cfg(5)| replace:: **vmm.cfg**\(5)
.. _vmm.cfg(5): vmm.cfg.5
.. non vmm
.. |postconf(1)| replace:: **postconf**\(1)
.. _postconf(1): http://www.postfix.org/postconf.1.html
.. |transport(5)| replace:: **transport**\(5)
.. _transport(5): http://www.postfix.org/transport.5.html
.. |today| date::
.. #EOF