Pipe to read from process output

Pipe to write into process input

Typedef for direction of movement from one quad to the next.

Edge of a quad including diagonal edges of masked quads if _corner_mask true.

Typedef for a polygon being a hole or not; clearer than using a boolean.

https://gist.github.com/terakun/b7eff90c889c1485898ec9256ca9f91d https://graphsharp.codeplex.com/SourceControl/latest#Source/Graph#/Algorithms/Layout/