GUI: prepare to improve pattern manager

src/engine/song.cpp

@@ -57,6 +57,12 @@ void DivSubSong::rearrangePatterns() {
   }
 }
 
+void DivSubSong::sortOrders() {
+}
+
+void DivSubSong::makePatUnique() {
+}
+
 void DivSong::clearSongData() {
   for (DivSubSong* i: subsong) {
     i->clearData();

src/engine/song.h

@@ -175,6 +175,8 @@ struct DivSubSong {
   void clearData();
   void optimizePatterns();
   void rearrangePatterns();
+  void sortOrders();
+  void makePatUnique();
 
   DivSubSong(): 
     hilightA(4),