Rename "CorporaIter" to "NgramIter". "NgramIter" require a reader of sentnces.
Change the order of arguments of "NewNgramIter".
The "order" is typed as "int".
COMMENT: Remove a needless comment.
"START_SYMOL" and "END_SYMBOL" are not used.
Remove needless codes.
Use "
" and "
" as special symols.
Merge branch 'feature/ngram-iter'