Returns a new S1ChordAngle that has been adjusted by the given error
bound (which can be positive or negative). "error" should be the value
returned by one of the error bound methods below. For example:
S1ChordAngle a(x, y);
S1ChordAngle a1 = a.PlusError(a.GetS2PointConstructorMaxError());
Returns a new S1ChordAngle that has been adjusted by the given error bound (which can be positive or negative). "error" should be the value returned by one of the error bound methods below. For example: S1ChordAngle a(x, y); S1ChordAngle a1 = a.PlusError(a.GetS2PointConstructorMaxError());