2009-11-11:
    correction bug in .unLoad function.
2009-10-15:
  - correction for deprecated basic regular expressions.
2009-08-19:
  - corrected documentation for mtable (\usepackage instead of usepackage)
  - completed documentation for contrasts generic
  - fixed bug in the internals for 'spss.portable.file':
    'SPSS Por' to ascii and 'SPSS Por' to integer translation tables
    were one item too short.
2009-06-02:
  - as.factor methods for item vectors adapted to new factor function
    in R 2.10.0
  - Fixed bug in sample.data.frame and sample.data.set methods:
    Samples were drawn only from the first m observations, where m is
    the number of variables in the data frame/data set.