Codechange: Use std::string when translating TTDP NewGRF string codes.

src/string_func.h

@@ -25,6 +25,7 @@
 #define STRING_FUNC_H
 
 #include <stdarg.h>
+#include <iosfwd>
 
 #include "core/bitmath_func.hpp"
 #include "string_type.h"
@@ -79,6 +80,7 @@ bool IsValidChar(WChar key, CharSetFilter afilter);
 
 size_t Utf8Decode(WChar *c, const char *s);
 size_t Utf8Encode(char *buf, WChar c);
+size_t Utf8Encode(std::ostreambuf_iterator<char> &buf, WChar c);
 size_t Utf8TrimString(char *s, size_t maxlen);
 
 
@@ -89,6 +91,14 @@ static inline WChar Utf8Consume(const char **s)
 	return c;
 }
 
+template <class Titr>
+static inline WChar Utf8Consume(Titr &s)
+{
+	WChar c;
+	s += Utf8Decode(&c, &*s);
+	return c;
+}
+
 /**
  * Return the length of a UTF-8 encoded character.
  * @param c Unicode character.