Come up with a comprehensive proposal for naming spatial modules and technologies [LUCENE-7202]

There are three different spatial implementations circulating at the moment, and nobody seems happy with the naming of them. For each implementation strategy, we need both a module name and a descriptive technology name that we can use to distinguish one from the other. I would expect the following people to have an interest in this process: @rmuir, @dsmiley, @mikemccand, etc.

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Migrated from [LUCENE-7202](https://issues.apache.org/jira/browse/LUCENE-7202) by Karl Wright (@DaddyWri), updated May 09 2016

Start by reviewing the three spatial implementations described in the issue and the migrated LUCENE-7202 discussion. Identify the module and descriptive technology naming needs for each implementation, then document a comprehensive proposal that distinguishes all three and addresses the concerns raised by the interested contributors.

Written by the indexing model from the issue text.