Renamed copy_list top copy_of_account_list.

This should make better what the variable is abount.
Made the smtp_connection private.

It's not of anyone else's business.
Added server_name field to the smtp_connection.

It may come handy soon.
Introduced server_name parameter in tcp_secure().
Added missing parameter for the title for the ssl error requester.
Now also shows the name of the remote server on an SSL failure.
Extract the sha256 key and present it as well to the user.
Added string fields for manually specifying the fingerprint.