The SubdivisionMethod class provides the names used to set the subdivision
method for a path as class variables.                                     

The subdivision method is used to determine the number of path curve    
points N created between two adjacent control points.                   

Valid subdivision method names are: 

   SPACING - Divide the distance D between adjacent control points by a 
             given spacing value S: N = D/S - 1 

   SUBDIVISION - Set N to a given subdivision number. 

   TOTAL - Appoximate the total number of path points using the number of 
           control points Nc and total numner Nt: N = (Nt-1)/(Nc-1) - 1 

   Get the valid subdivision method names.