Provide mode flag to ResetToInitialConditions() to skip the execution…

… of RunIC() (#466)

src/FGFDMExec.cpp

@@ -604,7 +604,9 @@ void FGFDMExec::ResetToInitialConditions(int mode)
 {
   if (Constructing) return;
 
-  if (mode == 1) Output->SetStartNewOutput();
+  // mode flags
+
+  if (mode & START_NEW_OUTPUT) Output->SetStartNewOutput();
 
   InitializeModels();
 
@@ -613,7 +615,8 @@ void FGFDMExec::ResetToInitialConditions(int mode)
   else
     Setsim_time(0.0);
 
-  RunIC();
+  if (!(mode & DONT_EXECUTE_RUN_IC))
+    RunIC();
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

src/FGFDMExec.h

@@ -460,10 +460,15 @@ class FGFDMExec : public FGJSBBase
   void Resume(void) {holding = false;}
   /// Returns true if the simulation is Holding (i.e. simulation time is not moving).
   bool Holding(void) {return holding;}
+  /// Mode flags for ResetToInitialConditions
+  static const int START_NEW_OUTPUT    = 0x1;
+  static const int DONT_EXECUTE_RUN_IC = 0x2;
   /** Resets the initial conditions object and prepares the simulation to run
-      again. If mode is set to 1 the output instances will take special actions
-      such as closing the current output file and open a new one with a
-      different name.
+      again. If the mode's first bit is set the output instances will take special actions
+      such as closing the current output file and open a new one with a different name.
+      If the second bit is set then RunIC() won't be executed, leaving it to the caller
+      to call RunIC(), e.g. in case the caller wants to set some other state like control
+      surface deflections which would've been reset.
       @param mode Sets the reset mode.*/
   void ResetToInitialConditions(int mode);
   /// Sets the debug level.