minor, fix foreign key

schema.sql

@@ -24,7 +24,8 @@ CREATE TABLE IF NOT EXISTS distributor (
 CREATE TABLE IF NOT EXISTS package (
 	id INTEGER AUTO_INCREMENT PRIMARY KEY, -- index
 	name TEXT NOT NULL UNIQUE,
-	family TEXT -- if this package it part of a more general package family
+	family INTEGER, -- if this package is part of a more general package family
+	FOREIGN KEY (family) REFERENCES package (id)
 );
 
 -- the part itself