Fixed a method that had the wrong return type

olla/include/kernels.h

@@ -73,7 +73,7 @@ public:
      * 
      * @param context    the context in which to execute this kernel
      */
-    virtual double execute(OpenMMContextImpl& context) = 0;
+    virtual void execute(OpenMMContextImpl& context) = 0;
 };
 
 /**

platforms/cuda/src/CudaKernels.cpp

@@ -82,7 +82,7 @@ static double calcEnergy(OpenMMContextImpl& context, System& system) {
 void CudaInitializeForcesKernel::initialize(const System& system) {
 }
 
-double CudaInitializeForcesKernel::execute(OpenMMContextImpl& context) {
+void CudaInitializeForcesKernel::execute(OpenMMContextImpl& context) {
 }
 
 CudaCalcHarmonicBondForceKernel::~CudaCalcHarmonicBondForceKernel() {

platforms/cuda/src/CudaKernels.h

@@ -63,7 +63,7 @@ public:
      * 
      * @param context    the context in which to execute this kernel
      */
-    double execute(OpenMMContextImpl& context);
+    void execute(OpenMMContextImpl& context);
 };
 
 /**

platforms/reference/src/ReferenceKernels.cpp

@@ -107,7 +107,7 @@ void disposeRealArray(RealOpenMM** array, int size) {
 void ReferenceInitializeForcesKernel::initialize(const System& system) {
 }
 
-double ReferenceInitializeForcesKernel::execute(OpenMMContextImpl& context) {
+void ReferenceInitializeForcesKernel::execute(OpenMMContextImpl& context) {
     double zero[] = {0.0, 0.0, 0.0};
     context.getForces().fillWithValue(zero);
 }

platforms/reference/src/ReferenceKernels.h

@@ -63,7 +63,7 @@ public:
      * 
      * @param context    the context in which to execute this kernel
      */
-    double execute(OpenMMContextImpl& context);
+    void execute(OpenMMContextImpl& context);
 };
 
 /**