Add shortcut for changing the Bank in performance load

In the performance load menu, the current Bank can be changed by pressing the switch and turning the knob left or right.

src/uimenu.cpp

@@ -1566,6 +1566,11 @@ void CUIMenu::PerformanceMenu (CUIMenu *pUIMenu, TMenuEvent Event)
 	unsigned nLastPerformance = pUIMenu->m_pMiniDexed->GetLastPerformance();
 	unsigned nValue = pUIMenu->m_nSelectedPerformanceID;
 	unsigned nStart = nValue;
+
+	unsigned nLastPerformanceBank = pUIMenu->m_pMiniDexed->GetLastPerformanceBank();
+	unsigned nBankValue = pUIMenu->m_nSelectedPerformanceBankID;
+	unsigned nBankStart = nValue;
+
 	if (pUIMenu->m_pMiniDexed->IsValidPerformance(nValue) != true)
 	{
 		// A bank change has left the selected performance out of sync
@@ -1633,6 +1638,42 @@ void CUIMenu::PerformanceMenu (CUIMenu *pUIMenu, TMenuEvent Event)
 			}
 			break;
 
+		case MenuEventPressAndStepDown:
+			do
+			{
+				if (nBankValue == 0)
+				{
+					// Wrap around
+					nBankValue = nLastPerformanceBank;
+				}
+				else if (nBankValue > 0)
+				{
+					--nBankValue;
+				}
+			} while ((pUIMenu->m_pMiniDexed->IsValidPerformanceBank(nBankValue) != true) && (nBankValue != nBankStart));
+			pUIMenu->m_nSelectedPerformanceBankID = nBankValue;
+			pUIMenu->m_pMiniDexed->SetParameter (CMiniDexed::ParameterPerformanceBank, nBankValue);
+			pUIMenu->m_pMiniDexed->SetFirstPerformance();
+			break;
+		
+		case MenuEventPressAndStepUp:
+			do
+			{
+				if (nBankValue == nLastPerformanceBank)
+				{
+					// Wrap around
+					nBankValue = 0;
+				}
+				else if (nBankValue < nLastPerformanceBank)
+				{
+					++nBankValue;
+				}
+			} while ((pUIMenu->m_pMiniDexed->IsValidPerformanceBank(nBankValue) != true) && (nBankValue != nBankStart));
+			pUIMenu->m_nSelectedPerformanceBankID = nBankValue;
+			pUIMenu->m_pMiniDexed->SetParameter (CMiniDexed::ParameterPerformanceBank, nBankValue);
+			pUIMenu->m_pMiniDexed->SetFirstPerformance();
+			break;
+
 		case MenuEventSelect:	
 			switch (pUIMenu->m_nCurrentParameter)
 			{