Dtreeviz

Add colors to support more than 10 target classes for classification:

* https://github.com/parrt/dtreeviz/pull/185
*

This release makes a small change that really improve the speed of `dtreeviz.interpretation.explain_prediction_plain_english()`.

See [Fix: xgb_decision_tree shouldGoLeftAtSplit -- massive-speed-up 182](https://github.com/parrt/dtreeviz/pull/182).

[Quick bug fix for scaling images](https://github.com/parrt/dtreeviz/issues/179).

Bug fix release: [closed PRs](https://github.com/parrt/dtreeviz/pulls?q=is%3Apr+is%3Aclosed+milestone%3A1.3.4)

Minor tweaks and improvements.

Fix compatibility issue with 0.18 release of graphviz; fixed by 90031de435247632b75292e862e9697bb06479ca