Create small class for the contour info

[prensing]

Right now, we use a dictionary to hold a bunch of things about a contour, such as bounding box values, area, etc. This is done so that we don't calculate these values multiple times.

We should create a small class to handle this. For each value, it can see if it has it, if not calculate it, and then return it.

Also, the class can hold extra info such as the reason that contour was cut (eg see 2021 galactic_search).