Enhanced category features
{@link org.apache.lucene.facet.index.params.FacetIndexingParams FacetIndexingParams} 
used by 
{@link org.apache.lucene.facet.enhancements.EnhancementsDocumentBuilder EnhancementsDocumentBuilder}
for adding 
{@link org.apache.lucene.facet.enhancements.CategoryEnhancement CategoryEnhancement}'s
to the indexing parameters, and accessing them during indexing and search.