QueryParsers do not support negative boosts [LUCENE-4378]

Negative query boosts have been supported at the "Query" object level for a long time (resulting in negative scores for matching documents), but evidently we never updated the QueryParsers to know about this - attempting to specify a negative boost in the query string results in a parse error.

we should probably add this to the parser grammer(s)

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Migrated from [LUCENE-4378](https://issues.apache.org/jira/browse/LUCENE-4378) by Chris M. Hostetter (@hossman), 1 vote, updated Dec 02 2014
Attachments: [LUCENE-4378-test.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-4378/LUCENE-4378-test.patch)
Linked issues:
- [SOLR-3278](https://issues.apache.org/jira/browse/SOLR-3278)

Start by examining the QueryParsers and their query-string grammar definitions to trace how boosts are parsed. Review the attached LUCENE-4378-test.patch for the expected regression coverage, then verify that query strings with negative boosts parse successfully and produce the intended negative scores.

Written by the indexing model from the issue text.