Use Phrase rather than Word, and remove Word struct.
Use GetPhraseNext() rather than GetCharNext(), and clear GetCharNext().
Let char and c/char-private.h retire. Character functions are moved into dict.c and dict-private.h
Rename GetPhraseFromDict() to GetVocabFromDict(), considering "vocabulary" contains both "phrase" and "word".
Rename GetPhraseNext() as GetVocabNext(), for the same consideration.

	Note: Original naming habit can be kept using __attribute__ alias.