A method to draw heatmap from given enrichment score matrix 

similar to [`iPAGE_draw_matrix.sh`](https://github.com/abearab/pager/blob/main/iPAGE_draw_matrix.sh)

___
This is useful for diverse downstream tasks from PAGE run, e.g. [Figure 5A](https://www.biorxiv.org/content/10.1101/2023.01.13.524005v1.full)