Marginal optimization of UDDF import

This speeds up Aquadivelog imports marginally by doing lookup to used
equipments only instead of all equipment ever used.

Signed-off-by: Miika Turkia <miika.turkia@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
User manual: document importing GPX files in companion app

Document the new "add" menu capabilities, partially as there are features still not
functional.
Documents the new feature with GPX files imports.
Corrects a typo.

Signed-off-by: Salvador Cuñat <salvador.cunat@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Fix bug in handling of fake SAMPLE_EVENT_PO2 events

In commit bcdd6192fe45 ("Show translated event names in tooltip") I was
too aggressive in replacing the checking for event names with checking for
event types. It turns out that we are abusing an existing event type in
the planner (and use a different event name to mark the difference). By
just checking for the type this now caused incorrect information to be
displayed in the info box (a simply "PO2 warning" on a Suunto D9 could
turn into a "Bailing out to OC" notice).

The correct fix is to get our own range of SAMPLE_EVENT_xxx numbers from
libdivecomputer. Once we have those, we can do this the right way. For now
we just fall back to also checking the event name (which is what I wanted
to get away from so translated names don't trip us up).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>