profile: port event unhiding to QtQuick

This has UI changes:
- The unhiding options are accessed by a field that appears when
  there are hidden events.
- Only event-types of this particular dive are unhidden.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/divecomputer.cpp

@@ -334,6 +334,12 @@ struct event *get_event(struct divecomputer *dc, int idx)
 	return &dc->events[idx];
 }
 
+bool divecomputer::has_individually_hidden_events() const
+{
+	return std::any_of(events.begin(), events.end(),
+			[] (const event &ev) { return ev.hidden; });
+}
+
 void add_extra_data(struct divecomputer *dc, const std::string &key, const std::string &value)
 {
 	if (key == "Serial") {