Contour Overlay

A simple program to overlay any figure with contour lines from the same or different data set as defined by the ContourMatrix, (see contourc). This allows information from two different images to be combined in one image.
Syntax:
coverlay(cm) - overlay current figure with contours defined by cm.
coverlay(cm,figh) - overlay figure pointed by figh with contours.
coverlay(...,LineSpec) - draws contours with line type and color as specified by LineSpec.
coverlay(...,Name,Value) - specify contour properties using one or more
property name, property value pairs, see Contour properties.

Typical usages is as follows:
cm = contourc(x,y,Z,n); - generate ContourMatrix
figh = imagesc(x,y,ZZ) or any other command that generates an image
ZZ may be a different matrix but with the same domain, x,y.
coverlay(cm,figh) - overlay the figure with contours.
clabel(cm,figh) - label the contours if desired.

Note:
It is important for the image domain to match the contours domain.
For example use the same X & Y vectors to specify both domains.