* mixi.el (mixi-object-timestamp): New accessor method.

* mixi.el (mixi-object-timestamp): New accessor method.
(mixi-cache-expired-p): Use it.
(mixi-object-realize-p): New alias.
(mixi-object-set-timestamp): New accessor method.
(mixi-object-touch): New macro.
(mixi-friend-realize-p): Abolish.
(mixi-friend-touch): Ditto.
(mixi-diary-realize-p): Ditto.
(mixi-diary-touch): Ditto.
(mixi-community-realize-p): Ditto.
(mixi-community-touch): Ditto.
(mixi-topic-realize-p): Ditto.
(mixi-topic-touch): Ditto.
(mixi-message-realize-p): Ditto.
(mixi-message-touch): Ditto.
(mixi-friend-realize): Follow the change above.
(mixi-diary-realize): Ditto.
(mixi-community-realize): Ditto.
(mixi-topic-realize): Ditto.
(mixi-message-realize): Ditto.