Implemented SettingsDatabase::remove

At the same time, fixed the order in the QuickOpen plugin to make sure
the RefreshInterval setting isn't immediately removed after saving it.

Also disabled debug output for settings database.

src/plugins/coreplugin/settingsdatabase.cpp

@@ -49,7 +49,7 @@
 using namespace Core;
 using namespace Core::Internal;
 
-enum { debug_settings = 1 };
+enum { debug_settings = 0 };
 
 namespace Core {
 namespace Internal {
@@ -67,7 +67,7 @@ public:
     QString effectiveKey(const QString &key) const
     {
         QString g = effectiveGroup();
-        if (!g.isEmpty())
+        if (!g.isEmpty() && !key.isEmpty())
             g += QLatin1Char('/');
         g += key;
         return g;
@@ -181,8 +181,25 @@ bool SettingsDatabase::contains(const QString &key) const
 
 void SettingsDatabase::remove(const QString &key)
 {
-    Q_UNUSED(key);
-    // TODO: Remove key and all subkeys
+    const QString effectiveKey = d->effectiveKey(key);
+
+    // Delete keys from the database
+    QSqlQuery query(d->m_db);
+    query.prepare(QLatin1String("DELETE FROM settings WHERE key = ? OR key LIKE ?"));
+    query.addBindValue(effectiveKey);
+    query.addBindValue(effectiveKey + QLatin1String("/%"));
+    query.exec();
+
+    // Remove keys from the cache
+    foreach (const QString &k, d->m_settings.keys()) {
+        // Either it's an exact match, or it matches up to a /
+        if (k.startsWith(effectiveKey)
+            && (k.length() == effectiveKey.length()
+                || k.at(effectiveKey.length()) == QLatin1Char('/')))
+        {
+            d->m_settings.remove(k);
+        }
+    }
 }
 
 void SettingsDatabase::beginGroup(const QString &prefix)

src/plugins/quickopen/quickopenplugin.cpp

@@ -206,8 +206,8 @@ void QuickOpenPlugin::saveSettings()
     if (core && core->settingsDatabase()) {
         Core::SettingsDatabase *s = core->settingsDatabase();
         s->beginGroup("QuickOpen");
-        s->setValue("RefreshInterval", refreshInterval());
         s->remove("");
+        s->setValue("RefreshInterval", refreshInterval());
         foreach (IQuickOpenFilter *filter, m_filters) {
             if (!m_customFilters.contains(filter))
                 s->setValue(filter->name(), filter->saveState());