(lrt-single-consonant-table): Several key sequence changed.
(lrt-composing-pattern-double-c): Handle a consonant with
semi-vowel-lower correctly.
(lrt-handle-maa-sakod): Do not reset quail-current-key.
(lrt-handle-tone-mark): Check the existence of double consonant
correctly.
(lrt-handle-maa-sakod): Correctly handle the case that quail-current-data
is nil.
(lrt-handle-tone-mark): Fix bug of handling key sequence "hhai" + tone.