squashed commit: mulit term_payload_clj_score; EWAHCompressedBitmap CodeTokenizer

* term_payload_clj_score:
  + rework the term_payload_clj_score to support multiple terms
    the ExpressionContext has visibility on all of them
    (works like boolean Should query, with minimum should match = 1)
  + remove the shared local_state, now it lives only once per ExpressionContext

* CodeTokenizer
  + switch from encoding each line number into 4 byte payload
    use EWAHCompressedBitmap bitmap and encode all matching lines in one
    payload (serialized EWAHCompressedBitmap)

  + removed the concept for important lines

* example app.rb
  + remove the complex clojure expression, that was basically
    doing AND for all matching lines for each occurance

    this was simply replaced by (.cardinality combined-bitmask)
    so now it is cheaper to service queries like 'int main void'
    or only 'int'
    more work will be done in that area (like do the AND ourselves)
  + show only 50 lines per document in the result page
  + rename the index from 'example-index' to 'example-index-bitmap'