GUI: prepare for a per-channel oscilloscope?

currently supported systems:
- Amiga
- AY-3-8910
- Dummy System
- OPLL
- SegaPCM

no trigger supported yet!

src/engine/platform/ay.h

@@ -56,6 +56,7 @@ class DivPlatformAY8910: public DivDispatch {
     };
     std::queue<QueuedWrite> writes;
     ay8910_device* ay;
+    DivDispatchOscBuffer* oscBuf[3];
     unsigned char regPool[16];
     unsigned char lastBusy;
   
@@ -90,6 +91,7 @@ class DivPlatformAY8910: public DivDispatch {
     void acquire(short* bufL, short* bufR, size_t start, size_t len);
     int dispatch(DivCommand c);
     void* getChanState(int chan);
+    DivDispatchOscBuffer* getOscBuffer(int chan);
     unsigned char* getRegisterPool();
     int getRegisterPoolSize();
     void flushWrites();