Test model compatibility. (dmlc#5248)

* Add model compability tests.

* Typo.

[RFC] Version 0.90 release candidate (dmlc#4475)

* Release 0.90

* Add script to automatically generate acknowledgment

* Update NEWS.md

Release 0.82 (dmlc#4201)

Release 0.81 version (dmlc#3864)

* Release 0.81 version

* Update NEWS.md

Release version 0.80 (dmlc#3541)

* Up versions

* Write release note for 0.80

Release version 0.72 (dmlc#3337)

Release version 0.71 (dmlc#3200)

Update PyPI maintainer; use VERSION for binary wheels (dmlc#2992)

Tag version 0.6 (dmlc#1422)

Update CHANGES.md