* mixi.el (mixi-post-error): New error symbol.

* mixi.el (mixi-post-error): New error symbol.
(mixi-post-error): New macro.
(mixi-post-form): New macro.
(mixi-make-form-data): New function.
(mixi-url-retrieve): Add optional argument `extra-headers'.
(mixi-url-post-form): New function.
(mixi-w3m-post-form): Ditto.
(with-mixi-post-form): New macro.
(mixi-post-diary-key-regexp): New constant.
(mixi-post-diary-id-regexp): Ditto.
(mixi-post-diary-title-regexp): Ditto.
(mixi-post-diary-body-regexp): Ditto.
(mixi-post-diary-succeed-regexp): Ditto.
(mixi-post-diary): New function.