gaZBGradEval:

--------------------------------------------------------------------------
   This evaluation function takes in a potential solution and two options
   options(3) is the percent of time to perform the gradient heuristic to 
   the potential solution
   options(4) is the percentage of time to update the solution based on 
   the outcome of the gradient heuristic

   Since version 7.
--------------------------------------------------------------------------
   Form:
   [nsol, val] = gaZBGradEval(sol,options)
--------------------------------------------------------------------------

   ------
   Inputs
   ------  
   sol
   options

   -------
   Outputs
   -------
   nsol
   val

--------------------------------------------------------------------------