QML UI: do not crash on selecting dive computers

For reasons unknown to me, the DCDeviceData instance was freed way too early,
and used afterwards, obviously resulting in a SIGSEGV. This commit creates
the DCDeviceData as a direct child of the QMLManager instance, ensuring
it does not get freed prematurely.

Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

core/downloadfromdcthread.cpp

@@ -16,11 +16,11 @@ static QString str_error(const char *fmt, ...)
 	return str;
 }
 
-DownloadThread::DownloadThread() : m_data(new DCDeviceData())
+DownloadThread::DownloadThread()
 {
+	m_data = DCDeviceData::instance();
 }
 
-
 void DownloadThread::run()
 {
 	auto internalData = m_data->internalData();

mobile-widgets/qmlmanager.cpp

@@ -91,7 +91,8 @@ QMLManager::QMLManager() : m_locationServiceEnabled(false),
 	m_updateSelectedDive(-1),
 	m_selectedDiveTimestamp(0),
 	m_credentialStatus(UNKNOWN),
-	alreadySaving(false)
+	alreadySaving(false),
+	m_device_data(new DCDeviceData(this))
 {
 #if defined(BT_SUPPORT)
 	// ensure that we start the BTDiscovery - this should be triggered by the export of the class

mobile-widgets/qmlmanager.h

@@ -18,6 +18,7 @@
 
 #include "core/btdiscovery.h"
 #include "core/gpslocation.h"
+#include "core/downloadfromdcthread.h"
 #include "qt-models/divelistmodel.h"
 
 class QMLManager : public QObject {
@@ -204,6 +205,7 @@ private:
 	bool checkDepth(DiveObjectHelper *myDive, struct dive *d, QString depth);
 	bool currentGitLocalOnly;
 	bool m_showPin;
+	DCDeviceData *m_device_data;
 
 signals:
 	void cloudUserNameChanged();