Remove mmaps related to characters.
Remove InitChar() and TerminateChar() processes.
Fix boundary condition of GetPhraseNext().
Remove buffers about character files, and modify char_cur_pos into int type.
Add comment for Str2Word().
Modify Str2Word() into new data representation.
Modify getCharFirst() to new data representation.
Modify GetCharNext() to new data representation.
Fix compilation error about keyNode.
Let static_data.tree be const.