reduce append calls for speedups
- http://golang.org/src/pkg/strconv/quote.go#L24
- http://golang.org/src/pkg/strconv/quote.go#L30
- http://golang.org/src/pkg/strconv/quote.go#L62
buf = append(buf, `\x`...)
buf = append(buf, lowerhex[s[0]>>4])
buf = append(buf, lowerhex[s[0]&0xF])
to
buf = append(buf, '\\', 'x', lowerhex[s[0]>>4], lowerhex[s[0]>>0xF])
and maybe move lowerhex into function