pixelwright 0.8.3

Natural construction plans can now build log buildings with plank roofs.

• "walls": "logs" (course px, default 3): the walls go down whole, a log at a time, seam and log together, the two faces in turn and each log from the front corner out; the gable's logs the same way; no corner posts or wall plates.
• "roofOrder": "boards" (board px, default 3): roof boards nailed on side by side from the front rake to the back, each whole from eave to ridge.

Plans without them build exactly as before. Learning L-065; one new test.