make parseCommand take an extra error stream argument

Change-Id: Ia56015e7e088f2ce5a28cf0747ca93fdee731f81
diff --git a/src/CParser.hpp b/src/CParser.hpp
index beb91ef..cb92b12 100644
--- a/src/CParser.hpp
+++ b/src/CParser.hpp
@@ -37,7 +37,7 @@
 class CParser {
 public:
     CParser(const CTree& tree);
-    cd_ parseCommand(const std::string& line);
+    cd_ parseCommand(const std::string& line, std::ostream& errorStream);
 
 private:
     const CTree& m_tree;