ShapeMatcher and ShapeValues [LUCENE-4388]

This patch provides two key interfaces: ShapeMatcher and ShapeValues. The ShapeMatcher concept is borrowed from @ryantxu's JtsGeoStrategy which has a similar GeometryTester. ShapeValues is basically a ValueSource/FunctionValues for shapes. This isn't working; I didn't modify any existing classes.

I haven't completely thought this through but a SpatialStrategy might expose a makeShapeValues(IndexReader) and/or makeCenterShapeValues(IndexReader) (the latter is the center points of indexed data). A generic Distance ValueSource could easily be implemented in terms of makeCenterShapeValues(). And a strategy could support any query shape simply by implementing makeShapeValues().

I've been thinking about how the API handles strategies supporting indexing multiple shapes and I wonder if that could happen simply via a new MultiShape<Shape>.

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Migrated from [LUCENE-4388](https://issues.apache.org/jira/browse/LUCENE-4388) by David Smiley (@dsmiley), updated Sep 17 2012
Attachments: [LUCENE-4388_ShapeValues_and_ShapeMatcher.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-4388/LUCENE-4388_ShapeValues_and_ShapeMatcher.patch)

Start by reviewing the attached LUCENE-4388_ShapeValues_and_ShapeMatcher.patch and the ShapeMatcher and ShapeValues interfaces it introduces. Read the proposed SpatialStrategy makeShapeValues(IndexReader) and makeCenterShapeValues(IndexReader) entry points; the issue does not define an agreed API or concrete completion criteria, so those must be established before implementation.

Written by the indexing model from the issue text.