UI: Add advanced audio properties dialog

This dialog gives options such as increasing audio past 100%, forcing
the audio of a source to mono, and setting the audio sync offset of a
source (which was an oft-requested feature)

obs/window-basic-main.cpp

@@ -619,6 +619,9 @@ OBSBasic::~OBSBasic()
 	if (transformWindow)
 		delete transformWindow;
 
+	if (advAudioWindow)
+		delete advAudioWindow;
+
 	ClearVolumeControls();
 	ui->sources->clear();
 	ui->scenes->clear();
@@ -1561,6 +1564,13 @@ void OBSBasic::on_action_Settings_triggered()
 	settings.exec();
 }
 
+void OBSBasic::on_actionAdvAudioProperties_triggered()
+{
+	advAudioWindow = new OBSBasicAdvAudio(this);
+	advAudioWindow->show();
+	advAudioWindow->setAttribute(Qt::WA_DeleteOnClose, true);
+}
+
 void OBSBasic::on_scenes_currentItemChanged(QListWidgetItem *current,
 		QListWidgetItem *prev)
 {