Add minNumberShouldMatch parameter to SpanNearQuery [LUCENE-7434]

On the user list, Saar Carmi asked about a new type of SpanQuery that would allow for something like BooleanQuery's minimumNumberShouldMatch

> Given a set of search terms (t1, t2, t3, ti), return all documents where in a sequence of x=10 tokens at least c=3 of the search terms appear within the sequence.

I _think_ we can modify SpanNearQuery fairly easily to accommodate this. I'll submit a PR in the next few days.



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Migrated from [LUCENE-7434](https://issues.apache.org/jira/browse/LUCENE-7434) by Tim Allison (@tballison), 1 vote, updated Sep 09 2016
Attachments: [a b c d e f mm=3.PNG](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-7434/a%20b%20c%20d%20e%20f%20mm%3D3.PNG) (versions: 2), [AllPairsNearSpans20160902.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-7434/AllPairsNearSpans20160902.patch), [FSA for repeating words.PNG](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-7434/FSA%20for%20repeating%20words.PNG), [TestMinShouldMatchSpan.java](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-7434/TestMinShouldMatchSpan.java) (versions: 2)
Linked issues:
- #4442

Start by reading SpanNearQuery and the attached TestMinShouldMatchSpan.java and AllPairsNearSpans20160902.patch. Determine how the proposed minimumNumberShouldMatch behavior fits the existing span-query model, then add focused tests for the sequence and match-count examples; done means the requested behavior is covered and the relevant tests pass.

Written by the indexing model from the issue text.