[common][id] add inequality check

frackit/common/id.hh

@@ -61,6 +61,12 @@ public:
     bool operator== (const Id& otherId) const
     { return id_ == otherId.get(); }
 
+    /*!
+     * \brief Inequality check.
+     */
+    bool operator!= (const Id& otherId) const
+    { return id_ != otherId.get(); }
+
 private:
     std::size_t id_;
 };

frackit/python/common/id.hh

@@ -34,6 +34,7 @@ void registerId(py::module& module)
     cls.def(py::init<std::size_t>());
     cls.def("get", &Id::get, "return the id");
     cls.def(py::self == Id());
+    cls.def(py::self != Id());
     cls.def(hash(py::self));
 }