Some bug fixes and [clean up](https://github.com/parrt/dtreeviz/milestone/20?closed=1).
1.2
See [Bugs fixes](https://github.com/parrt/dtreeviz/milestone/18?closed=1) and [pull requests](https://github.com/parrt/dtreeviz/milestone/18?closed=1).
The main improvement is the introduction of support for LightGBM, thanks to tlapusan.
1.1.4
See [issues addressed](https://github.com/parrt/dtreeviz/milestone/17?closed=1)