Merge pull request #1372 from peastman/const

Marked usesPeriodicBoundaryConditions() as const

openmmapi/include/openmm/System.h

@@ -243,7 +243,7 @@ public:
      *
      * @return true if at least one force uses PBC and false otherwise
      */
-    bool usesPeriodicBoundaryConditions();
+    bool usesPeriodicBoundaryConditions() const;
 private:
     class ConstraintInfo;
     Vec3 periodicBoxVectors[3];

openmmapi/src/System.cpp

@@ -133,7 +133,7 @@ void System::setDefaultPeriodicBoxVectors(const Vec3& a, const Vec3& b, const Ve
     periodicBoxVectors[2] = c;
 }
 
-bool System::usesPeriodicBoundaryConditions() {
+bool System::usesPeriodicBoundaryConditions() const {
 
     bool uses_pbc = false;
     bool all_forces_implement = true;