add IG square state versions

[elmeraa-usgs]

This MR makes square (1080 x 1080 pt) cartogram content for states of interest:

Deleware

Maryland

[cnell-usgs]

There's a lot of repeated code in the functions here that makes this fairly inefficient and challenging to make edits to. Most of the code is the same but the dimensions or positioning changes.

Go back through your ig and cart_state functions and re-use the existing functions. You may need to add parameters to the inputs for output dimensions, or nudging placement. You really only need a couple plotting functions - one to make the cartogram and one for the national view. These can be re-used to make the other formats by providing filtered data as an input.