#118 — New task emails have redundant and missing information

- The recipient email address is not always redundant: when two persons are assigned to the task, both names and addresses appear there. We can make it smarter though.

- The task title sometimes appears in the email subject and sometimes not (then only 'New Task assigned' is printed). It could be that the title gets lost when it is too long. Or perhaps it always goes wrong when quick-adding the task with kss.

As an aside, I have made the email code in Products.Poi smarter to work well with i18n - some of those changes may need to go in here as well. That took a lot of debugging though - fortunately with a bug reporter that was really diligent in following up and trying out new fixes. And there is another bug report just in that is probably going to cost me some hours again. Doing this right across browsers, email programs and intermediate email servers is really hard. I could certainly look at making the xm email sending code smarter.

I made some changes in r76173 relating to issues #92 and #124, which should have solved this issue as well.