Being interested in NameOwnerChanged for a namespace, not one name

[Will Thompson]

So following some discussion about this at LPC, I updated my 
implementation to only match on arg0, and only match period-separated 
prefixes (not just any string prefix). So the new key is now arg0namespace.

The branch defining, implementing and testing it is at 
<http://git.collabora.co.uk/?p=user/wjt/dbus.git;a=shortlog;h=refs/heads/arg0namespace>; 
it's linked from <https://bugs.freedesktop.org/show_bug.cgi?id=24317> if 
anyone fancied reviewing it.

(I also got Ryan to explain why argXpath works how it does, and 
documented it and added tests: 
<https://bugs.freedesktop.org/show_bug.cgi?id=31818>.)

Cheers,
-- 
Will