core: create qPrefGeocoding from SettingsObjectWrapper

Update set/get functions to follow common name scheme:
- get function have same name as in struct preferences
- set function have set_<name>
- signal function have <name>_changed

one class one .h/.cpp is the C++ idiom. Having load/sync of each
variable in 1 functions (in contrast to the distributed way
SettingsObjectWrapper handles it) secures the same storage name
is used. Having the set/get/load/sync functions grouped together
makes it easier to get an overview.

REMARK: this commit only defines the class, it is not active in production

Signed-off-by: Jan Iversen <jani@apache.org>

core/settings/qPrefGeocoding.h

@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef QPREFGEOCODING_H
+#define QPREFGEOCODING_H
+#include "core/pref.h"
+
+#include <QObject>
+
+
+class qPrefGeocoding : public QObject {
+	Q_OBJECT
+	Q_PROPERTY(taxonomy_category first_taxonomy_category READ first_taxonomy_category WRITE set_first_taxonomy_category NOTIFY first_taxonomy_category_changed);
+	Q_PROPERTY(taxonomy_category second_taxonomy_category READ second_taxonomy_category WRITE set_second_taxonomy_category NOTIFY second_taxonomy_category_changed);
+	Q_PROPERTY(taxonomy_category third_taxonomy_category READ third_taxonomy_category WRITE set_third_taxonomy_category NOTIFY third_taxonomy_category_changed);
+
+public:
+	qPrefGeocoding(QObject *parent = NULL);
+	static qPrefGeocoding *instance();
+
+	// Load/Sync local settings (disk) and struct preference
+	void loadSync(bool doSync);
+	void load() { loadSync(false); }
+	void sync() { loadSync(true); }
+
+public:
+	taxonomy_category first_taxonomy_category() { return prefs.geocoding.category[0]; }
+	taxonomy_category second_taxonomy_category() { return prefs.geocoding.category[1]; }
+	taxonomy_category third_taxonomy_category() { return prefs.geocoding.category[2]; }
+
+public slots:
+	void set_first_taxonomy_category(taxonomy_category value);
+	void set_second_taxonomy_category(taxonomy_category value);
+	void set_third_taxonomy_category(taxonomy_category value);
+
+signals:
+	void first_taxonomy_category_changed(taxonomy_category value);
+	void second_taxonomy_category_changed(taxonomy_category value);
+	void third_taxonomy_category_changed(taxonomy_category value);
+
+private:
+	void disk_first_taxonomy_category(bool doSync);
+	void disk_second_taxonomy_category(bool doSync);
+	void disk_third_taxonomy_category(bool doSync);
+};
+
+#endif