Util: add split_with_entities() function, which is imported from Main::PSGI::View. It will be re-used by Input::Twitter.
Util: add =for test_synopsis block to POD to avoid Test::Synopsis error.
Main::PSGI::View: substitute Util::split_with_entities() with _split_text_with_entities().
Input::Twitter: add transform_html_unescape. This is necessary because twitter.com HTML-escapes some special characters.