Introduce View Menu

* Move user interface settings from the settings widget into the view menu.
* Add auto-restart prompt to make theme changes easy

src/main.cpp

@@ -155,6 +155,12 @@ int main(int argc, char** argv)
 
     int exitCode = Application::exec();
 
+    // Check if restart was requested
+    if (exitCode == RESTART_EXITCODE) {
+        QProcess* proc = new QProcess();
+        proc->start(QCoreApplication::applicationFilePath());
+    }
+
 #if defined(WITH_ASAN) && defined(WITH_LSAN)
     // do leak check here to prevent massive tail of end-of-process leak errors from third-party libraries
     __lsan_do_leak_check();