add getHistoryFile getter

aql2/src/prompt/Prompt.h

@@ -58,6 +58,10 @@ public:
 	cli::Environment & getEnvironment ( ) {
 		return m_environment;
 	}
+
+	const std::string & getHistoryFile ( ) const {
+		return m_history_file;
+	}
 };
 #endif /* _AQL_PROMPT_H_ */