Add notifySampleChanged in dispatch and engine:

This method/variables are for notify sample is changed/altered/added/removed.  can be called together with updateSampleTex for sample update.

multipcm: Fix possible desync with instrument and sample parameter

opl4: Split sample table render and sample data render, Add notifySampleChange for refresh sample parameters

src/gui/newSong.cpp

@@ -289,6 +289,7 @@ void FurnaceGUI::drawNewSong() {
     orderCursor=-1;
     samplePos=0;
     updateSampleTex=true;
+    notifySampleChange=true;
     selStart=SelectionPoint();
     selEnd=SelectionPoint();
     cursor=SelectionPoint();