rule: carry over all table attributes (including family)

fixes https://github.com/google/nftables/issues/150

rule.go

@@ -89,6 +89,9 @@ func (cc *Conn) GetRule(t *Table, c *Chain) ([]*Rule, error) {
 		if err != nil {
 			return nil, err
 		}
+		// Carry over all Table attributes (including Family), as the Table
+		// object which ruleFromMsg creates only contains the name.
+		r.Table = t
 		rules = append(rules, r)
 	}