Isolate the C function from the Clipper Extend System

 The first step is to create a pure C function that does not have any
 Clipper Extend system code in it.   This function should be created
 and prototyped as a normal C function.  Next we create a small
 function that contains all the Extend System interface code.  This is
 the function we actually call from Clipper.  It is this function that
 contains all of the Extend System code to retrieve parameters from
 Clipper, and to return a value back to Clipper.   Since the pure C
 function actually performs the work, we gain the ability to call it
 from other C functions as well as from Clipper.

 This means we can optionally compile a Clipper Extend System
 interface function or a C Main function, and either one will work
 properly.  The ability to compile the function as a stand alone
 program is a great help when testing and debugging.  The goal should
 be to create a fully functional, stand alone program, that works
 correctly before trying to interface it to Clipper.