Make pad argument of GetPanel default to 0.

sample/PGEX_SMX.h

@@ -14,7 +14,7 @@ public:
     //DOWN is 0x80
     //LEFT is 0x08
     //Add these bytes together to get the combination (all 4 held down is 0xAA
-    HWButton GetPanel(Key k,int pad)const{
+    HWButton GetPanel(Key k,int pad=0)const{
         return panelState[k-UP];
     };
     void EnableLogMessages(bool enabled){