Tue Oct 09 2012
1. Changes 
   * the output of a fitted model is now a S4 class object consisting of print, "[", "[<-" and summary methods.
   * drop "$" to get an element of the output object.

2. New features 
   * add macros to do weighting on all the levels when using IGLS.

Thu Oct 18 2012
1. New features
   * add functionality to centre the explanatory variables.