2019-04-19 version 1.2.10:
* Optimze MessagePack.unpack not to copy source string
2019-03-13 version 1.2.9:
* Hotfix release only for JRuby: 1.2.8-java was built incorrectly
2019-03-11 version 1.2.8:
* Fix a regression that MessagePack#unpack raises error if IO is assigned as the (only) argument
* Improve compatibility that MessagePack#pack returns nil if IO is assigned as 2nd argument
2019-03-01 version 1.2.7:
* Add Packer#write_bin and Packer#write_bin_header methods