Merge branch 'hotfix/0.1.11'
Merge branch 'release/0.1.12'
Merge branch 'release/0.1.13'
Merge branch 'release/0.2.0'
Merge branch 'release/0.3.0'
make decayed value monoid a separate class
Merge pull request #223 from tsdeng/separate_decayed_value_monoid

Separate decayed value monoid