Explicitly include needed include file

The Q_DECLARE_TR_FUNCTIONS macro is defined in QCoreApplication, so let's
make sure that's included.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Show translated event names in tooltip

In order for this to work we need to compare against the event type
instead of the event name - which makes much more sense to do, anyway.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Fix test for "air" in tooltip display of gaschange

The "is_air()" test works when we have the gases in permille, but not in
percent. In that case we can just check for He == 0 and O2 == 21.

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