Updated write from ZString to not pass by reference.

MString.cpp

@@ -232,7 +232,7 @@ namespace coreutils {
       return *this;
    }
    
-   MString &MString::write(ZString &value) {
+   MString &MString::write(ZString value) {
       int len = length;
       setSize(length + value.getLength());
       memcpy(data + len, value.getData(), value.getLength());