Resurrect json cache to try sharded doc store for features.
Use fnv hash of feature id for indexing. #67.
Setup structure for preserving docs despite collisions.
Update tests, other integration with feature retrieval.
Report cache load stats.
Display shard load total.
Merge branch 'dev' into dev-docpack

Conflicts:
	scripts/collisions.js
	test/fixtures/mem.json
Merge branch 'dev' into dev-docpack

Conflicts:
	lib/index.js
include feature patch key.
Opimization: simplify how we get to heuristic value.
Optimization: Less function calls.
Index loaddoc optimizations.
Optimize: degens as array.
Update debug code.
Call bind less.
Merge branch 'dev' into dev-docpack
Store docs as JSON strings in memory.
Keep track of known terms.
Skip expensive merge operations if current state is null.
Update s3 api for packed json docs.