Change origin

[I-Am-Umbrella]

Add ability to change pen origin to any of the four corners of the paper.

[alexrudd2]

My best guess as to what's setting the plot origin is here:

saxi/src/planning.ts

Lines 519 to 524 in 3e9ae84

	function constantAccelerationPlan(points: Vec2[], profile: AccelerationProfile): XYMotion {
	const dedupedPoints = dedupPoints(points, epsilon);
	if (dedupedPoints.length === 1) {
	return new XYMotion([new Block(0, 0, 0, dedupedPoints[0], dedupedPoints[0])]);
	}
	const segments = dedupedPoints.slice(1).map((a, i) => new Segment(dedupedPoints[i], a));