Skip empty voices while scrolling (#466)

* Skip empty voices while scrolling

* Added more cases where the voice is empty

* Filter out "EMPTY     "

To be used together with a curated collection of banks that use the name `EMPTY     ` instead of `INIT VOICE`

---------

Co-authored-by: probonopd <probonopd@users.noreply.github.com>

src/uimenu.cpp

@@ -581,6 +581,19 @@ void CUIMenu::EditProgramNumber (CUIMenu *pUIMenu, TMenuEvent Event)
 		return;
 	}
 
+	string voiceName = pUIMenu->m_pMiniDexed->GetVoiceName (nTG); // Skip empty voices
+	if (voiceName == "EMPTY     "
+	    || voiceName == "          "
+	    || voiceName == "----------"
+	    || voiceName == "~~~~~~~~~~" )
+	{
+		if (Event == MenuEventStepUp) {
+			CUIMenu::EditProgramNumber (pUIMenu, MenuEventStepUp);
+		}
+		if (Event == MenuEventStepDown) {
+			CUIMenu::EditProgramNumber (pUIMenu, MenuEventStepDown);
+		}
+	} else {
 		string TG ("TG");
 		TG += to_string (nTG+1);
 
@@ -591,6 +604,7 @@ void CUIMenu::EditProgramNumber (CUIMenu *pUIMenu, TMenuEvent Event)
 					      Value.c_str (),
 					      nValue > 0, nValue < (int) CSysExFileLoader::VoicesPerBank-1);
 	}
+}
 
 void CUIMenu::EditTGParameter (CUIMenu *pUIMenu, TMenuEvent Event)
 {