FUNCTION:  ClassSize - find conjugacy class Sizes,    
CALLING SEQUENCE:  ClassSize(w,R);,                   ClassSize(R);
    ,PARAMETERS:  R = a root system data Structure
             w = a list of integers representing a member of W(R)
SYNOPSIS:   
  If R is a root system of Rank n, members of the Coxeter group W(R) are
  represented as lists of integers in the range 1..n. The group element
  corresponding to w = [i_1,...,i_l] is the product of the generators
  Indexed by i_1,...,i_l. The Indexing follows Base(R).
  ClassSize(w,R) returns the Size of the conjugacy class of w in W(R).
  ClassSize(R) returns a list of the Sizes of every conjugacy class of
  W(R), following the same order as the one used by the functions ClassRep,
  Cprod, PermChar, Induce, IrrChars, and Restrict.
  The conjugacy class Sizes for the exceptional groups E-F-H are read
  from prestored lists in the Coxeter/lib subdirectory. The lists for the
  remaining irreducible cases are generated "on demand".
  For a description of root system data Structures, see Coxeter[Structure].
EXAMPLES:   ,  ClassSize([4,3,2,1,2,1],H4);     yields           720
  ClassSize(w0,A2*G2);             yields            3
  ClassSize(C3);                   yields   [1,6,8,3,6,3,6,1,6,8],    
SEE ALSO:  Base, ClassRep, Cprod, PermChar, Induce, IrrChars,
           Restrict, Structure):
