added missing implementation file for getAllVariableNames

src/getAllVariableNames.cc

+#include "getAllVariableNames.h"
+
+namespace ChimeraTK{
+
+  std::set< std::string > getAllVariableNames( boost::shared_ptr<ControlSystemPVManager> csManager ){
+    std::set< std::string > output;
+    for (auto & pv : csManager->getAllProcessVariables()){
+      output.insert(pv->getName());
+    }
+
+    return output;
+  }
+
+} //  namespace ChimeraTK
+