Email enhancements

Perhaps this is misfiled, but I'd like developers be able to be notified whenever something is assigned to them.
Assuming they were subscribed to every project, the don't need a notice when something changes, only when the change directly affects them.

For issues:
Status/content of an issue assigned to me changed
An issue was assigned to me
An issue assigned to me was reassigned

And the same for projects.
The project bit is harder, because you have to be subscribed.
I think this breaks that model (for the better)

I wouldn't mind fiddling with it if something like this would just 'plug in'.