add "force mono audio" option and fix flags not be

ing set after a dispatch reset

src/engine/dispatchContainer.cpp

@@ -88,7 +88,7 @@ void DivDispatchContainer::clear() {
   prevSample[1]=temp[1];*/
 }
 
-void DivDispatchContainer::init(DivSystem sys, DivEngine* eng, int chanCount, double gotRate, bool pal) {
+void DivDispatchContainer::init(DivSystem sys, DivEngine* eng, int chanCount, double gotRate, unsigned int flags) {
   if (dispatch!=NULL) return;
 
   bb[0]=blip_new(32768);
@@ -170,7 +170,7 @@ void DivDispatchContainer::init(DivSystem sys, DivEngine* eng, int chanCount, do
       dispatch=new DivPlatformDummy;
       break;
   }
-  dispatch->init(eng,chanCount,gotRate,pal);
+  dispatch->init(eng,chanCount,gotRate,flags);
 }
 
 void DivDispatchContainer::quit() {

src/engine/engine.cpp

@@ -5993,6 +5993,7 @@ bool DivEngine::initAudioBackend() {
   }
 
   lowQuality=getConfInt("audioQuality",0);
+  forceMono=getConfInt("forceMono",0);
 
   switch (audioEngine) {
     case DIV_AUDIO_JACK:

src/engine/engine.h

@@ -116,7 +116,7 @@ struct DivDispatchContainer {
   void acquire(size_t offset, size_t count);
   void fillBuf(size_t runtotal, size_t size);
   void clear();
-  void init(DivSystem sys, DivEngine* eng, int chanCount, double gotRate, bool pal);
+  void init(DivSystem sys, DivEngine* eng, int chanCount, double gotRate, unsigned int flags);
   void quit();
   DivDispatchContainer():
     dispatch(NULL),
@@ -148,6 +148,7 @@ class DivEngine {
   bool metronome;
   bool exporting;
   bool halted;
+  bool forceMono;
   int ticks, curRow, curOrder, remainingLoops, nextSpeed, divider;
   int cycles, clockDrift;
   int changeOrd, changePos, totalSeconds, totalTicks, totalTicksR, totalCmds, lastCmds, cmdsPerSecond, globalPitch;
@@ -568,6 +569,7 @@ class DivEngine {
       metronome(false),
       exporting(false),
       halted(false),
+      forceMono(false),
       ticks(0),
       curRow(0),
       curOrder(0),

src/engine/playback.cpp

@@ -1192,5 +1192,12 @@ void DivEngine::nextBuf(float** in, float** out, int inChans, int outChans, unsi
   memcpy(oscBuf[0],out[0],size*sizeof(float));
   memcpy(oscBuf[1],out[1],size*sizeof(float));
   oscSize=size;
+
+  if (forceMono) {
+    for (size_t i=0; i<size; i++) {
+      out[0][i]=(out[0][i]+out[1][i])*0.5;
+      out[1][i]=out[0][i];
+    }
+  }
   isBusy.unlock();
 }