1. Unbreak multiple recipient specification on the command line.
2. Make it apparent that -t actually is for parsing recipients from a message
body.
3. Use the email module with some minimal parsing to avoid unnecessary breakage
down the line because of ad hoc header parsing method previously employed.
4. Make send_mail a bit more robust / atomic.
5. Don't override library modules (email).
6. Remove dupe modules.
7. Simplify code a bit more (it could be simplified even further, but this is
good enough for now).
This will fix mass emailing, which affects SMART reports at least if multiple
recipients are specified.
This addresses ticket # 960.
