update FieldSelectorResult with a BREAK only result option. consolidate some of the state for break/load [LUCENE-2535]

some field storage strategies can be much improved by immediate break vs. the break-and-load currently provided.
this adds another break option, which makes it more advantageous to have member variables of the enum that indicate it's a break/load etc. vs. doing a bunch of grouped == checks.

The BREAK option should cause an early termination with include == false in the ParallelReader when the BREAK before any other field, then the document should not be loaded from that reader. This is fairly easy to validate with a test, which is included in the patch.

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Migrated from [LUCENE-2535](https://issues.apache.org/jira/browse/LUCENE-2535) by Woody Anderson, updated May 09 2016
Attachments: [LUCENE_4.0-2535.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2535/LUCENE_4.0-2535.patch), [LUCENE-2535.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2535/LUCENE-2535.patch)

Start with FieldSelectorResult and the ParallelReader behavior described in the issue, then inspect the attached LUCENE_4.0-2535.patch and LUCENE-2535.patch for the intended test and affected files. Verify that BREAK before any other field terminates early with include == false and avoids loading the document from that reader; the included test should demonstrate this behavior.

Written by the indexing model from the issue text.