Patch query - single email per bug

[Kevin Benton]

Has anyone written a patch to make BZ send just one email per bug?  I
have one here as a local customization.  It allows our mail servers to
kill some of the duplicate emails that are going out (due to members of
lists getting notified along with being included for other reasons). 
It's also reducing the load on the server because it only makes one call
to sendmail instead of one per recipient.  I'd like to include it in the
public release.

Before I send it up for review, I wanted to get feedback on the idea
first.  I plan to implement a flag to enable/disable this feature named
OneEmailPerBug with a status of on/off.

Kevin