Merge branch 'develop' of github.com:danil-lashin/iavl into develop

* 'develop' of github.com:danil-lashin/iavl:
  Prep Release 0.11.0 (cosmos#111)
  Remove architecture dependent getter functions (cosmos#96)
  Use 8 bytes to store int64 components of database keys  (cosmos#107)
  Update to CircleCI 2.0 (cosmos#108)
  Release 0.10.0: Update Changelog and bump version (cosmos#99)
  delete empty file (relict from merging master into develop)
  Mutable/Immutable refactor and GetImmutable snapshots (cosmos#92)
  Remove unreachable code
  Remove unused variable
  dep: Change tendermint dep to be ^v0.22.0 (cosmos#91)
  Fix benchmark scripts for current code (cosmos#89)
  release v0.9.2 (cosmos#82)
  Various lints (cosmos#80)
  Jae/rangeprooffix (cosmos#75)