This function converts the object X
into an object of class "layered".
The argument X should contain some kind of spatial data
such as a point pattern, window, or pixel image.
If X is a simple object then it will be converted into
a layered object containing only one layer which is equivalent
to X.
If X can be interpreted as consisting of
multiple layers of data, then the result will be a layered
object consisting of these separate layers of data.
if X is a list of class "listof" or "solist",
then as.layered(X) consists of several layers,
one for each entry in the list X;
if X is a multitype point pattern,
then as.layered(X) consists of several layers,
each containing the sub-pattern consisting of points of one type;
if X is a vector-valued measure,
then as.layered(X) consists of several layers,
each containing a scalar-valued measure.