Correct multiple issues with database saving

* Mark the database as clean after fully completing the file save operation INSTEAD of when merely writing the database to a file.

* Stop the modified timer when marking the database as clean, this prevents latent erroneous modified signals from being emitted.

* Do not restart the modified timer after a new change is detected while it is still running.

src/gui/DatabaseWidget.cpp

@@ -1370,7 +1370,7 @@ bool DatabaseWidget::lock()
     if (m_db->isModified()) {
         bool saved = false;
         // Attempt to save on exit, but don't block locking if it fails
-        if (config()->get("AutoSaveOnExit").toBool()) {
+        if (config()->get("AutoSaveOnExit").toBool() || config()->get("AutoSaveAfterEveryChange").toBool()) {
             saved = save();
         }