Cast exponent in pow() function to RealOpenMM, to avoid overload ambiguity...

Cast exponent in pow() function to RealOpenMM, to avoid overload ambiguity error on Windows when RealOpenMM is defined as double.

plugins/freeEnergy/platforms/reference/src/SimTKReference/ReferenceFreeEnergyLJCoulomb14Softcore.cpp

@@ -78,7 +78,7 @@ ReferenceFreeEnergyLJCoulomb14Softcore::~ReferenceFreeEnergyLJCoulomb14Softcore(
     
     cutoff = true;
     cutoffDistance = distance;
-    krf = pow(cutoffDistance, -3.0f)*(solventDielectric-1.0f)/(2.0f*solventDielectric+1.0f);
+    krf = pow(cutoffDistance, (RealOpenMM)-3.0)*(solventDielectric-1.0f)/(2.0f*solventDielectric+1.0f);
     crf = (1.0f/cutoffDistance)*(3.0f*solventDielectric)/(2.0f*solventDielectric+1.0f);
             
     return ReferenceForce::DefaultReturn;

plugins/freeEnergy/platforms/reference/src/SimTKReference/ReferenceFreeEnergyLJCoulombSoftcoreIxn.cpp

@@ -89,7 +89,7 @@ ReferenceFreeEnergyLJCoulombSoftcoreIxn::~ReferenceFreeEnergyLJCoulombSoftcoreIx
     cutoff = true;
     cutoffDistance = distance;
     neighborList = &neighbors;
-    krf = pow(cutoffDistance, -3.0f)*(solventDielectric-1.0f)/(2.0f*solventDielectric+1.0f);
+    krf = pow(cutoffDistance, (RealOpenMM)-3.0)*(solventDielectric-1.0f)/(2.0f*solventDielectric+1.0f);
     crf = (1.0f/cutoffDistance)*(3.0f*solventDielectric)/(2.0f*solventDielectric+1.0f);
 
     return ReferenceForce::DefaultReturn;