Fix the jojo-mode that caused an error.
Thanks to the anonymous person who reported the problem.

* twittering-mode.el: Fix the jojo-mode that caused an error when
the condition of automatically posting a tweet was satisfied.
Thanks to the anonymous person who reported the problem.
(twittering-post-predicted-message-like-jojo): fix variable name.
Fix a return value of `twittering-render-replied-statuses'.
Thanks to Ikumi Keita who reported the problem.

* twittering-mode.el: Fix a return value of
`twittering-render-replied-statuses'. The function returns nil
without regard to whether a tweet is rendered or not. Thanks to
Ikumi Keita who reported the problem.
(twittering-render-replied-statuses): fix a return value.
Support different intervals of retrieving timelines.

* twittering-mode.el: Support different intervals of retrieving
timelines.
(twittering-relative-retrieval-interval-alist): new variable.
(twittering-relative-retrieval-count-alist): new variable.
(twittering-retrieve-timeline): reset the retrieval count.
(twittering-start): update all active timelines forcibly once.
(twittering-get-relative-interval): new function.
(twittering-get-retrieval-count): new function.
(twittering-set-retrieval-count): new function.
(twittering-initialize-retrieval-count): new function.
(twittering-update-active-buffers): reduce retrievals according to
the variable `twittering-relative-retrieval-interval-alist'.