Refactor concave pipe layout

[JamesBremner]

The L-shaped room pipe layout works well. See https://github.com/JamesBremner/pipify#pipe-layout-in-a-l-shaped-room

However, modifying this to handle other concave rooms ( backwards L, upside down L, etc ) has proven to be a challeng.

So I have decided to refactor the code, so has to more easily handle other concave room shapes.

[JamesBremner]

[JamesBremner]