[kkc] add support for Direct Input Mode (#5) Direct Input Mode is not the same as Latin Mode in libkkc. And Direct Input is normally used as the Japanese Kana-kanji conversion instead of Latin. For example, anthy's "Latin" equals libkkc's "Direct Input", the Zenkaku_Hankaku key is mapped to switch "set-input-mode-{direct,hiragana}" in libkkc.
