possibly solve vZoom/vScroll issue

move these to a new DivInstrumentTemp struct
this way, undo history is not altered every time these change

issue #2179

src/engine/fileOps/ftm.cpp

@@ -358,7 +358,6 @@ void copyMacro(DivInstrument* ins, DivInstrumentMacro* from, int macro_type, int
 
   to->len = from->len;
   to->delay = from->delay;
-  to->lenMemory = from->lenMemory;
   to->mode = from->mode;
   to->rel = from->rel;
   to->speed = from->speed;
@@ -390,7 +389,6 @@ void copyMacro(DivInstrument* ins, DivInstrumentMacro* from, int macro_type, int
 
     wave->len = to->len;
     wave->delay = to->delay;
-    wave->lenMemory = to->lenMemory;
     wave->mode = to->mode;
     wave->rel = to->rel;
     wave->speed = to->speed;

src/engine/instrument.h

@@ -266,11 +266,6 @@ struct DivInstrumentMacro {
   // 0-31: normal
   // 32+: operator (top 3 bits select operator, starting from 1)
   unsigned char macroType;
-  
-  // the following variables are used by the GUI and not saved in the file
-  int vScroll, vZoom;
-  int typeMemory[16];
-  unsigned char lenMemory;
 
   explicit DivInstrumentMacro(unsigned char initType, bool initOpen=false):
     mode(0),
@@ -280,12 +275,8 @@ struct DivInstrumentMacro {
     speed(1),
     loop(255),
     rel(255),
-    macroType(initType),
-    vScroll(0),
-    vZoom(-1),
-    lenMemory(0) {
+    macroType(initType) {
     memset(val,0,256*sizeof(int));
-    memset(typeMemory,0,16*sizeof(int));
   }
 };
 
@@ -1002,6 +993,20 @@ struct DivInstrumentPOD {
   }
 };
 
+struct DivInstrumentTemp {
+  // the following variables are used by the GUI and not saved in the file
+  int vScroll[160];
+  int vZoom[160];
+  int typeMemory[160][16];
+  unsigned char lenMemory[160];
+  DivInstrumentTemp() {
+    memset(vScroll,0,160*sizeof(int));
+    memset(vZoom,-1,160*sizeof(int));
+    memset(typeMemory,0,160*16*sizeof(int));
+    memset(lenMemory,0,160*sizeof(int));
+  }
+};
+
 struct MemPatch {
   MemPatch() :
     data(NULL)
@@ -1044,6 +1049,8 @@ struct DivInstrumentUndoStep {
 struct DivInstrument : DivInstrumentPOD {
   String name;
 
+  DivInstrumentTemp temp;
+
   DivInstrument() :
     name("") {
       // clear and construct DivInstrumentPOD so it doesn't have any garbage in the padding