Fix #48

[vphpersson]

Use the correct index for the extraction of the hook attribute value.

[vphpersson]

My guess is that the code has in fact worked for you, but endianess is causing the code not to work for me. In that case the solution needs to be a little bit more complicated. Maybe something like this?

var hookIndex int
if nativeEndian == binary.LittleEndian {
	hookIndex = 2
} else {
	hookIndex = 3
}
hook := ad.Bytes()[hookIndex]
a.Hook = &hook

[florianl]

thanks for your contribution!