Merge branch 'release/2.1.2' into develop
Checking of payload state; no more safe/unsafe distinction within CTE
Cleaned up tests, removed references to unsupported "useCache" param
Added developer documentation
Some comments; CountThenEstimateBytes -> BytesRefUtils refactoring
Refactored term lists to use BytesRefHash; also serialization test
Special handling of ordinals is no longer helpful - removed
Since we are using the term hash codes, get ES to precalculate them
Streamlined this executor and collector somewhat
Minor term list efficiency improvements
Experiments with Post-mode aggregation -- not complete
Code comments
Consistency in error reporting
More comments, and package rearrangement
Sampling mode for term list facet
Added heuristic for loading field data with/without hashes
Updated version numbers
Merge branch 'release/2.1.3'

Conflicts:
	src/main/java/com/pearson/entech/elasticsearch/search/facet/approx/termlist/InternalStringTermListFacet.java