Add the ability to configure mail sending according to actions

We have found that the included maillistener is sending out too many emails. E.g. if a developer changes the status of an issue from [Assigned] to [In Progress], he gets a mail himself teling about the change.

I assume I can cirumvent this by making my own listener but it would be nice to have a simple matrix by which the email sending could be configured, e.g.

There are three possible recipients of the emails: The reporter, the assignee and the watchers (those watching the issue).

It ought to be possible to make a matrix where you could link which actions should e mailed to which recipients - as depicted below

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Reporter Assignee Watchers
Created x
Assigned x x
Commented x x x
Updated
Resolved x x
Reopened x x x
Closed x x x

Notify on own changes [ ] Yes [x] No

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The last option to avoid, e.g., the one providing comments to get an email with the comments.

However, this would require the database (or a property file) to contain specific listener information which you might prefer to avoid ...