Add: std::back_insert_iterator<std::string> Utf8Encode function

src/string.cpp

@@ -672,6 +672,11 @@ size_t Utf8Encode(std::ostreambuf_iterator<char> &buf, WChar c)
 	return Utf8Encode<std::ostreambuf_iterator<char> &>(buf, c);
 }
 
+size_t Utf8Encode(std::back_insert_iterator<std::string> &buf, WChar c)
+{
+	return Utf8Encode<std::back_insert_iterator<std::string> &>(buf, c);
+}
+
 /**
  * Properly terminate an UTF8 string to some maximum length
  * @param s string to check if it needs additional trimming

src/string_func.h

@@ -94,6 +94,7 @@ 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 Utf8Encode(std::back_insert_iterator<std::string> &buf, WChar c);
 size_t Utf8TrimString(char *s, size_t maxlen);