Q object for complexed queries has been introduced

[nobrin]

Q object, may likes Django's one, has been introduced. @1fb3f1dc575e4b3ce3dd71198023cd2a774b7cbf
It enables this.

members = Member.select(Q(name="Fortune") | Q(group__name="Happiness Charge"))

This will be converted into this SQL.

SELECT "member".* FROM "member"
INNER JOIN "group" AS "member.group" ON "member"."group_id" = "member.group"."id"
WHERE (((("member"."name" = ?) OR ("member.group"."name" = ?))))