[Feature Request] Adding parameters to customize xaxis in the treeplot

[illumination-k]

Thanks for your great project!

The treeplot of compareClusters is great to summarize enrichment results. But if we use long labels for the cluster names, we cannot read labels because of the overlap, so we want to change the parameters of xaxis in heatmap and scatter plots.

How about adding parameters to customize xaxis in the treeplot like angles and offsets? Or can I open the PR?