Revision 647747

  Implement a random substitution feature; requires a requesttemplate, 
  one or more substitution variables of the form ${varname) in the 
  requesttemplate and a substitution file formatted with one value 
  per newline delimited line (more than one variable per URL permitted).  
  The variables and files are referred to as subst variables and subst 
  files.  Each time the URL is sent the subst variable is replaced with 
  one line randomly selected from the subst file.  Any part of the 
  requesttemplate can be randomly substituted, protocol, host, port, etc.  
  
  The algorithm tries to make the creation time of the substitution 
  independent of the size of the subst file.  The randomness of the 
  selection can be adversely impacted if the sizes of the different 
  entries in the subst file vary considerably.

Submitted by: Guy Ferraiolo <guyf cnet.com>