This routine sorts the 'full' neutron beam (given by xw,yw)
in xc,yc channels. These can be imagined as cavities.
CavitiesOut sorts these channels back to normal coordinates.
Example: Slit(xw=0.05, yw=0.05, xc=4, yc=1)
WARNING: This is a contributed Component.
Parameters in boldface are required;
the others are optional.