support FileLoader in RCV1
support FileLoader in Gov2, small case
fix bug: there might be '\036' inside body field ...
fix bug: should not stem very long term
update btree: use rewind when allocate()
truncate wildcard query when size==1
truncate words with digits to reduce Btree size...
refactor
refactor
fix bug: parser will still fail if \n\37\n is not satisfied
refactor out body field
support colorized snippet
fix bug: during scoring, we didn't stem query to fetch qid
fix bug: there might be \n\37\n inside body field, so sad
factor out summarizer for non-score queries
add tests for gov2: index_00034.txt
refactor fstream, increase posbuff for gov2 dataset