CenterStage Object Class:  DataFromCurve
Subclass of:  Curve
Requires a reference to a Curve object

The DataFromCurve class provides a means of using the data already computed
by another Curve object.  One reason to do this is to change the coloring
or domain style without having to recompute the data.  Another is to make a
ShowMe checkbox that can be used to turn the curve on and off without
recomputing it (or any other objects linked to it).  To do this, make a
Curve object that has its OBJECT/SHOW menu set to NEVER, and then create a
DataFromCurve object that links to it and has the CheckBox and ShowMe
directives.  When the DataFromCurve object is first shown, it will force
the Curve object to compute the data, and then the DataFromCurve object
will be able to use that data whenever it is shown, without recomputing it.

The DataFromCurve object has no non-standard directives.