Tue Jan 15 2013
1. Bugs fixing by Thomas Arkens
   * add multiple categorical variables in the fixed terms.
   * fix the reference categories (by changing to the level number of the factor object in R.)
2. Changes
   * in sixway(), replace getOption("device")() by windows(), so the package works in Rstudio.

Thu Nov 15 2012
1. New features
   * add various options for calculating residuals at all levels.   

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

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.
