typed.go
func (t Typed) Ints64(key string) []int64 {
	return t.Ints64Or(key, nil)
}
func (t Typed) Ints64(key string) []int64 {
	return t.Ints64Or(key, nil)
}
// Returns an slice of ints64, or the specified slice
// Some conversion is done to handle the fact that JSON ints
// are represented as floats.