Allow using one password for incoming and outgoing server

[cketti]

In most cases users only have one email password. It's used for authentication to both the incoming server and the outgoing server.
But right now the passwords for both servers are completely separate in K-9 Mail. While users only have to enter the password once during initial setup, they have to enter it twice when the password changes, once for the incoming server and once for the outgoing server.

The probably easiest way to link the two passwords is to have a check box in the outgoing server settings that reads "use incoming server password".

[hseg]

This just bit me - trying to fix an issue with gmail had me change passwords. Having forgotten that passwords need to be configured in two different places, I only updated the outgoing server. Cue confusion when K9 complained it couldn't read email. So I try changing passwords again, and blindly don't notice I'm updating a different server. So now sending doesn't work. Cue Benny Hill music.