Make relative times default in planner 2

In planning you usually plan lengths of segments rather than runtimes to
leave a level.

This patch superseeds a previous one with a similar name and (even more)
broken spacing.

Signed-off-by: Robert C. Helling <helling@atdotde.de>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>