Since an algorithm can use more than one sweep, the sweep class doesn't
fit very good as it is right now. For this reasen it got converted to a
more general class named algorithm, that shall be used as parent for
every individual algorithm. The exact behaviour of the algorithm is
then defined in the child classes.
The sort function takes a list of Point objects and sorts them either
by their x or y coordinate using merge sort.
Also added a method set_random, that sets the coordinates to random
values and a method str, that returns the coordinates as string.
The module defines a LineSegment class that displays a line segment in
two-dimensional coordinate system. It is defined by a start- and an
endpoint. It also contains a method to calculate the length.
The point module defines a Point class, that displays a Point in a
two-dimensional coordinate system. An object of the class contains a x-
and y-coordinate and a setter and getter method for each at this point.
