Parametric Divided Box with Sliding Top

I started with Aaron Ciuffo's excellent lesson on parametric design, rewrote and restructured his code a bit, and added more customization options. I had to make some customizations to his work to get the lid to fit properly after printing on my printer, so I decided to roll those up into a customizer in case others had similar issues.

Highlights:
- Can define variable sized compartments now in both x and y directions
- Auto calculate box size based on compartment and wall/divider thickness