release v0.15.0
- remove visualization directory as it is being moved to a common respository
- update tests to support lightgbm 3.0 update
- optimize data mapper memory usage
- update CDN path for widget
- add mimic explainer test for high-dimensional dense raw features explanation
- fix lightgbm 3.0 support by densifying input matrix to reenable tests
- fix issues with importing version in setup.py before dependencies installed