Improve spatial package.html to compare Strategys [LUCENE-4223]

[asfimport]

Spin off from #5245. One of the most important parts of using the spatial module is deciding which Strategy fits your needs. We should improve the package.html documentation so that it compares the Strategys, focusing on:

• Underlying index format (lon/lat numeric fields vs grid terms vs ...)
• Multi-value support
• Indexable Shapes
• Queryable Shapes
• Query operations

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Migrated from LUCENE-4223 by Chris Male, updated Jul 23 2012

[asfimport]

David Smiley (@dsmiley) (migrated from JIRA)

I added some docs in trunk r1364782 (4x: 1364785) This included SpatialExample.java

We now need to document the strategies.