* VerifyItem takes no index; Return keys/values in range; Fix

* Bump version

* 0.9.1 -- compute hash from rangeproof

* Require Verify() before Verify*()

* Review fixes from #75

* adhere to: ineffassign, misspell, golint

* unexport helper function & godoc compatibility for package comments

*  _PathToLeaf -> pathToLeaf

* remove obsolete proof-types from doc

* comment exported method and unexport debug helper method
 
* remove unused private methods

* remove unnecessary else blocks (golint):

* remove unused named returns

* minor changes to make code more idiomatic

* consistent receiver names

 * omit type from declaration

 * remove brackets from single return val

Signed-off-by: Liamsi <[email protected]>

- bump version
- update changelog

Signed-off-by: Liamsi <[email protected]>

* Fix benchmark scripts for current code
* Add benchmark result

This is done to remove the need for an override constraint for tendermint
in the sdk.

Closes #90

* Move orphaningTree logic into VersionedTree

* Move Tree.Set and Node.set to VersionedTree, fix tests

* Move Tree.Remove and node.remove to VersionedTree

* Rename VersionedTree/Tree to MutableTree/ImmutableTree

* Rename files to match type names

* Add GetImmutable and lazy loading of MutableTree

* Move balance and rotate from Node to MutableTree

* Add benchmarks with -benchmem, remove incomplete benchmark

* Rename variables in rotation functions

* Add test to check for consistent tracking of orphans

* Add back ability to load old versions with idempotent saves

* Add idempotent save test case

# Conflicts:
#	CHANGELOG.md
#	Gopkg.lock
#	basic_test.go
#	doc.go
#	immutable_tree.go
#	node.go
#	proof.go
#	proof_range.go
#	tree_dotgraph_test.go
#	util.go
#	versioned_tree.go

Fix `go vet` failures