Imitialize gc y range for GF factor print

It seemed so smart to just base the coordinates on what's already in the
graphics context. Except that we apparently got a 0 to 0 range for y
coordinates if there are no pressure samples for a dive.

This fixes the problem and GF values are shown even for dives without
pressure samples.

Reported-by: Miika Turkia <miika.turkia@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Correctly reset stop depth if we receive NDL sample from libdivecomputer

The existing code forgot to reset the stopdepth to 0 which resulted in a
bogus safety stop being displayed on some divecomputers after the diver
finished their deco obligation.

Reported-by: Jan.Schubert <Jan.Schubert@GMX.li>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Fix compiling, old api of parse_xml_buffer

Commit 8843ee61 changes the api of 'parse_xml_buffer'. Unfortunately one
occurrence has been left which fails if LIBZIP has been defined.

Signed-off-by: Martin Gysel <me@bearsh.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>