Per SOLR-773, create field types that hid the details of creating tiers, geohash and lat/lon fields.
Fields should take in lat/lon points in a single form, as in:
<field name="foo">lat lon</field>
Incorporate Local Lucene/Solr
Implement Spatial Filter
Refactor XMLWriter startTag to allow arbitrary attributes to be written
Allow a single field type to index multiple fields
Inner class FieldCacheSources should be refactored into their own classes