This function generates a random pattern of points
in a ``stratified random'' sampling design. It can be useful
for generating random spatial sampling points. The bounding rectangle of `win`

is divided into
a regular $nx \times ny$ grid of rectangular tiles.
In each tile, `k`

random points are generated independently
with a uniform distribution in that tile.

Some of these grid points may lie outside the window `win`

:
if they do, they are deleted.

The result is a point pattern inside the window `win`

.

This function is useful in creating dummy points for quadrature
schemes (see `quadscheme`

) as well as in simulating
random point patterns.