Set up an initial Engine method importing functionality from ACORN library

There already are a number of functions in the ACORN library that might be ported in BHoM.
Try starting with a simple one.
1. Choose a simple method to be ported
2. Create engine method as appropriate (be it a Compute/Query/etc)
3. Port the code into the engine method. Do appropriate conversions as needed
4. Try testing it in Grasshopper, comparing with existing ACORN script