nowadays, many servers offer STARTTLS on the default IMAP port 143
instead of (or in addition to) the traditional IMAP over SSL/TLS (IMAPS)
on port 993.
this patch has been fixed up somewhat by the maintainer.
while at it, add/fix some licenses/copyrights/comments:
- it makes no sense to have a GPL exception in scripts
- ted did not contribute to the man page
- tst_timers is not part of the mbsync executable
- explicitly put the build system under GPL and add copyrights