GitLab

* break huge lines in sklearn tests

* break huge line in plotting tests

* break huge lines in basic tests

* multiple enhancements in engine tests

* multiple enhancements in sklearn tests

* hotfixes

* break huge lines and use with statement in C API test

* make NDCG test more strict

* removed excess import

* added tests for plotting trees in Python

* refined module_INSTALLED mechanism

* added note about that create_tree_digraph is better than plot_tree

* fixed grammar

* fixed params description in graph plotting functions

* clarified types of attributes in their descriptions

* increased readability of graphs by adding spaces

* added precision parameter to plot tree functions

https://docs.pytest.org/

* refine plot

* use warnings

* refine  logic

* revert 'move to compat.py'

* add plot metrics

* move 'raise Exception' to check_not_tuple_of_2_elements

* rename 'plot_metrics' to 'plot_metric'

* fix misleading message/docs

* change 'Metrics' in title to 'Metric'

* fix misleading comment

* add plot tree

* add docs

* add example

* add test

* fix test

* fix decision type

* add show_info

* use feature name if available

* add plot importance

* add plot example