seconds are too coarse for what we intend. technically, centisecs would
be sufficient (and more honest, given that we prefer coarse timers,
which have only tick precision), but that's a somewhat untypical unit.
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
