Add location_at(parameter, x_dir=)

[gumyr]

When creating sketches along a path the x_direction is typically unknown which leads to one having to potentially rotate the objects in the sketch. By allowing the x_direction to be controlled this would be avoided. The problem is illustrated in this example:

wall_length = 100

with BuildPart() as wall:
    with BuildLine():
        path = Polyline((-50, -40), (50, -40), (50, 40), (-50, 40), close=True)

    with BuildSketch(path ^ 0) as profile:
        t = Trapezoid(10, 15, 85, rotation=-90)
        top_line = t.edges().sort_by(Axis.X)[-1]
        with Locations(top_line @ 0.5):
            Circle(top_line.length / 2)

    sweep(path=path, transition=Transition.RIGHT)