This algorithm generates a realisation of the Simple Sequential
Inhibition point process
inside the window win. Starting with an empty window, the algorithm adds points
one-by-one. Each new point is generated uniformly in the window
and independently of preceding points. If the new point lies
closer than r units from an existing point, then it is rejected
and another random point is generated.
The algorithm terminates either when the desired number n
of points is reached, or when the current point configuration
has not changed for giveup iterations.