typed.go
func (t Typed) StringsOr(key string, d []string) []string {
	n, ok := t.StringsIf(key)
	if ok {
		return n
	}
	return d
}
func (t Typed) StringsOr(key string, d []string) []string {
	n, ok := t.StringsIf(key)
	if ok {
		return n
	}
	return d
}
// Returns an slice of strings, or the specified slice
// if the key doesn't exist or isn't a valid []string