Outgoing E-Mail

Outgoing E-Mail at the moment in acs-mail-lite is split in a multitude of procedures, some of the doublicating the efforts of the other. To clean this up I propose the following (in general):

•  Replace acs-mail-lite::send with acs-mail-lite::complex_send, making it a wrapper for complex_send or the other way round (rename complex_send to send and so on).
• Only support sending of e-mails via SMTP. Use smtp::sendmessage from TCLLIB for it (as does complex_send).
• Daveb suggested to split up complex_send to make it easier to test parts of it. Here are some ideas:
• Sub procedure to generate "to/cc/bcc/_lists" which are used in the respective TO/CC/BCC header. This will also clean up the sending of individual emails.
  
• HAve only one call to smtp::sendmessage and one hook for the complex_send callback.
• Suprocedure to append file tokens. Not sure this is useful as we need to do upvar for the tokens and could not do automated tests on them anyway. So I'd not do it.
• Have only one sweeper (the complex_sweeper) with support for multiple mail sending servers (so you can have multiple mail senders in the cluster instead of only one).
• Split of incoming email handing into a seperate file
• Delete acs-mail-lite-procs.tcl :-). Just kidding, but deprecate most of the procedures.

Sadly it is not a straightforward approach, as there is a catch. Using smtp::sendmessage forces us to figure out a new way for setting the bounce-email address header, as the old approach will not work anymore (using the SMTP command "FROM" set to the bounce address). I suggest to use the "Errors-To" Header instead as discussed at http://www.expita.com/header1.html although it is not official standard.