Update autotopic.c

version to v0.1.1-alpha
allow debugging to both debug window and system log (for when the stupid plugin causes a crash); disabled in source by default
autotopic_handle_topic_change now properly handles a NULL chatroom topic.
chat_joined_cb no longer calls autotopic_handle_topic_change directly, but instead sets up a glib timeout for CHAT_JOINED_TOPIC_CHECK_TIMER seconds to call check_topic_cb, which then calls autotopic_handle_topic_change instead.