prepare for deferred config saving

issue #1723

src/engine/engine.cpp

@@ -4013,11 +4013,13 @@ bool DivEngine::init() {
   return true;
 }
 
-bool DivEngine::quit() {
+bool DivEngine::quit(bool saveConfig) {
   deinitAudioBackend();
   quitDispatch();
-  logI("saving config.");
-  saveConf();
+  if (saveConfig) {
+    logI("saving config.");
+    saveConf();
+  }
   active=false;
   for (int i=0; i<DIV_MAX_OUTPUTS; i++) {
     if (oscBuf[i]!=NULL) delete[] oscBuf[i];

src/engine/engine.h

@@ -220,7 +220,7 @@ struct DivDispatchContainer {
   void fillBuf(size_t runtotal, size_t offset, size_t size);
   void clear();
   void init(DivSystem sys, DivEngine* eng, int chanCount, double gotRate, const DivConfig& flags, bool isRender=false);
-  void quit();
+  void quit(bool saveConfig=true);
   DivDispatchContainer():
     dispatch(NULL),
     bbInLen(0),

src/gui/gui.cpp

@@ -7242,8 +7242,12 @@ void FurnaceGUI::commitState() {
   }
 }
 
-bool FurnaceGUI::finish() {
+bool FurnaceGUI::finish(bool saveConfig) {
   commitState();
+  if (saveConfig) {
+    logI("saving config.");
+    saveConf();
+  }
   rend->quitGUI();
   ImGui_ImplSDL2_Shutdown();
   quitRender();

src/gui/gui.h

@@ -2735,7 +2735,7 @@ class FurnaceGUI {
     bool detectOutOfBoundsWindow(SDL_Rect& failing);
     int processEvent(SDL_Event* ev);
     bool loop();
-    bool finish();
+    bool finish(bool saveConfig=false);
     bool init();
     bool requestQuit();
     FurnaceGUI();