Minor Description
I noticed the ReRank query parser adds the score from the reRankQuery to the original score. This means that existing edismax boost functions can't easily be migrated to use reranking instead, and reranking functions have the same issue as is noted at https://solr.apache.org/guide/solr/latest/query-guide/dismax-query-parser.html#bq-bf-shortcomings.
In https://github.com/apache/solr/pull/1431 I've added a reRankOperator=multiply option to the ReRank parser which enables reranking functions to multiply the score instead. A reRankOperator=replace option is available too, enabling the reranked scores to be independent of the original scores.
