Make it so that getRandomNumberSeed by default returns a osrngseed() result,

rather than some pre-set seed generated at construction time.

Any call to "setRandomNumberSeed" prevents this behavior (unless the generator
is seeded with 0).

openmmapi/include/openmm/AndersenThermostat.h

@@ -35,6 +35,7 @@
 #include "Force.h"
 #include <string>
 #include "internal/windowsExport.h"
+#include "openmm/internal/OSRngSeed.h"
 
 namespace OpenMM {
 
@@ -104,6 +105,8 @@ public:
      * Get the random number seed.  See setRandomNumberSeed() for details.
      */
     int getRandomNumberSeed() const {
+        if (randomNumberSeed == 0)
+            return osrngseed();
         return randomNumberSeed;
     }
     /**

openmmapi/include/openmm/MonteCarloAnisotropicBarostat.h

@@ -36,6 +36,7 @@
 #include "Vec3.h"
 #include <string>
 #include "internal/windowsExport.h"
+#include "openmm/internal/OSRngSeed.h"
 
 namespace OpenMM {
 
@@ -159,6 +160,8 @@ public:
      * Get the random number seed.  See setRandomNumberSeed() for details.
      */
     int getRandomNumberSeed() const {
+        if (randomNumberSeed == 0)
+            return osrngseed();
         return randomNumberSeed;
     }
     /**

openmmapi/include/openmm/MonteCarloBarostat.h

@@ -35,6 +35,7 @@
 #include "Force.h"
 #include <string>
 #include "internal/windowsExport.h"
+#include "openmm/internal/OSRngSeed.h"
 
 namespace OpenMM {
 
@@ -115,6 +116,8 @@ public:
      * Get the random number seed.  See setRandomNumberSeed() for details.
      */
     int getRandomNumberSeed() const {
+        if (randomNumberSeed == 0)
+            return osrngseed();
         return randomNumberSeed;
     }
     /**

openmmapi/include/openmm/MonteCarloMembraneBarostat.h

@@ -35,6 +35,7 @@
 #include "Force.h"
 #include <string>
 #include "internal/windowsExport.h"
+#include "openmm/internal/OSRngSeed.h"
 
 namespace OpenMM {
 
@@ -212,6 +213,8 @@ public:
      * Get the random number seed.  See setRandomNumberSeed() for details.
      */
     int getRandomNumberSeed() const {
+        if (randomNumberSeed == 0)
+            return osrngseed();
         return randomNumberSeed;
     }
     /**

openmmapi/src/AndersenThermostat.cpp

@@ -37,7 +37,7 @@ using namespace OpenMM;
 
 AndersenThermostat::AndersenThermostat(double defaultTemperature, double defaultCollisionFrequency) :
         defaultTemp(defaultTemperature), defaultFreq(defaultCollisionFrequency) {
-    setRandomNumberSeed(osrngseed());
+    setRandomNumberSeed(0);
 }
 
 ForceImpl* AndersenThermostat::createImpl() const {

openmmapi/src/MonteCarloAnisotropicBarostat.cpp

@@ -31,13 +31,12 @@
 
 #include "openmm/MonteCarloAnisotropicBarostat.h"
 #include "openmm/internal/MonteCarloAnisotropicBarostatImpl.h"
-#include "openmm/internal/OSRngSeed.h"
 
 using namespace OpenMM;
 
 MonteCarloAnisotropicBarostat::MonteCarloAnisotropicBarostat(const Vec3& defaultPressure, double temperature, bool scaleX, bool scaleY, bool scaleZ, int frequency) :
         defaultPressure(defaultPressure), temperature(temperature), scaleX(scaleX), scaleY(scaleY), scaleZ(scaleZ), frequency(frequency) {
-    setRandomNumberSeed(osrngseed());
+    setRandomNumberSeed(0);
 }
 
 ForceImpl* MonteCarloAnisotropicBarostat::createImpl() const {

openmmapi/src/MonteCarloBarostat.cpp

@@ -31,13 +31,12 @@
 
 #include "openmm/MonteCarloBarostat.h"
 #include "openmm/internal/MonteCarloBarostatImpl.h"
-#include "openmm/internal/OSRngSeed.h"
 
 using namespace OpenMM;
 
 MonteCarloBarostat::MonteCarloBarostat(double defaultPressure, double temperature, int frequency) :
         defaultPressure(defaultPressure), temperature(temperature), frequency(frequency) {
-    setRandomNumberSeed(osrngseed());
+    setRandomNumberSeed(0);
 }
 
 ForceImpl* MonteCarloBarostat::createImpl() const {

openmmapi/src/MonteCarloMembraneBarostat.cpp

@@ -31,14 +31,13 @@
 
 #include "openmm/MonteCarloMembraneBarostat.h"
 #include "openmm/internal/MonteCarloMembraneBarostatImpl.h"
-#include "openmm/internal/OSRngSeed.h"
 
 using namespace OpenMM;
 
 MonteCarloMembraneBarostat::MonteCarloMembraneBarostat(double defaultPressure, double defaultSurfaceTension, double temperature, XYMode xymode, ZMode zmode, int frequency) :
         defaultPressure(defaultPressure), defaultSurfaceTension(defaultSurfaceTension), temperature(temperature),
         xymode(xymode), zmode(zmode), frequency(frequency) {
-    setRandomNumberSeed(osrngseed());
+    setRandomNumberSeed(0);
 }
 
 ForceImpl* MonteCarloMembraneBarostat::createImpl() const {