Hnet

* fixed d3graph version to 1.0.3

* added doi

* bug fix that utils does not exists
* docstrings added

* Small improvements

* fix for summarizing matrix using fishers method. The max value is taken for the column when its inf.

* New functionality to summarize associations into categories using fishers method. This can be done using the summarize=True in the plots
* New functionality regarding feature importance. This can be plotted using hn.plot_feat_importance()
* bug fix for removing background labels.
* styling and cleaning