Add features for the visualization of vector files

[Yimsun97]

Thank you for your contribution to this project and the documents on the webchat official account. I am recently working on the visualization of geographical vectors, but it appears that your code is readily applicable to the raster file at the moment (please point out if I miss anything). As far as I know, the geopandas is preferable to the kind of tasks but the default legends might be not easy to read (see the conversation on the default legends of geopandas).
I have written some utility functions for the discrete colorbars that are commonly seen in the papers, but I am not sure if these code are applicable to other cases. I am wondering how to keep flexibility and convenience at the same time. Do you have the time and interest to add the new features of vector visualzation in the future?