Sender Address Columns Vaatii uudelleenkäynnistyksen

Adds optional columns to the Thread Pane to allow sorting email messages by:
* Full sender address -- e.g. "[email protected]"
* Sender's domain -- e.g. "example.com"
* Sender's local part -- e.g. "someone"
* Sender's TLD -- e.g. ".com"