t/Main_PSGI_View.t: add test for bb_timestamp function.
t/Main_PSGI_View.t: add test for bb_status_permalink function.
Config: revise specifications of *_entity_{url,text}_builder config items. Text builders are necessary if you want to expand the t.co URL.
Main, Main::PSGI::View: implement default status_permalink_builder config item. Implement bb_status_permalink() template function. Pass the test.
Main: change the spec of get_timeline_config() method. It used to return undef if the requested timeline does not exist in the main. Now it returns main's config in that case. This is safer catch-all behavior.
status.tt: render permalink with bb_status_permalink() function.
Input::Generator: set status.busybird.status_permalink to empty string. That prevents BusyBird to link the status to twitter.com.
t/Main_PSGI_View, t/Status.t: move tests for autolinking from t/Status.t to t/Main_PSGI_View.t
t/WebAPI_html.t, t/Status.t: move tests about status ID rendering from t/Status.t to t/WebAPI_html.t
t/Main_PSGI_View: add tests for rendering status text containing Twitter Entities.
t/Main_PSGI_View.t: add a test about Twitter Entities.
Main: implement default *_entity_*_bulder config items.