string output bug in format.abc.Writer

format.abc.Writer outputs the number of characters instead of the number of bytes when writing strings. This causes errors when outputting special characters. The following code fixes the problem:

```
class ABCWriter extends format.abc.Writer {
override function writeString( s : String ) {
var encoding = null;
#if neko
var b = untyped new Bytes(s.length,s.__s);
#else
var b = Bytes.ofString(s, encoding);
#end
writeInt(b.length);
o.writeFullBytes(b,0,b.length);
}
}
```