Version 1.22.1
  * replaced two calls to 'class' to 'inherits'

Version 1.19.1
  * more robust versions of getTime and getWavelength

Version 1.17.1
  * replaced deprecated recycling of array of length 1 with vector of
    the correct length
  * getAllPeaks now no longer returns peaks with zero width

Version 1.3.1
  * corrected bug in preprocess concerning data matrices without dimnames