Serious work on JString and some minor MString ajustments.

JString.h

@@ -83,7 +83,9 @@ namespace coreutils {
       
       JString & operator=(coreutils:: ZString value) {	 
 	 std::cout << "operator=" << value << std::endl;
-
+	 setSize(value.getLength());
+	 memcpy(data, value.getData(), value.getLength());
+	 length = value.getLength();
 	 return *this;
       }