Favor pointers over references

The use of a pointer instead of a reference conveys the message that the
lifetime of the object being pointed can, and most likely will, exceed the
lifetime of the function.

Also shuffled the member variables and internal functions around and
removed unneeded function declarations.

server/modules/routing/schemarouter/session_command.hh

@@ -79,7 +79,4 @@ private:
     uint8_t  m_command;   /**< The command being executed */
     uint64_t m_pos;       /**< Unique position identifier */
     bool     m_reply_sent; /**< Whether the session command reply has been sent */
-
-    SessionCommand();
-    SessionCommand& operator = (const SessionCommand& command);
 };