10/27/08 - Improvements to slplot, bugfixes and a show method
02/27/08 - Replaced usage of exprSet class with ExpressionSet
04/10/07 - Added robustSVD, a SVD implementation robust to outliers
01/02/07 - Added a Non-linear PCA algorithm.
12/11/06 - kEstimate interface has changed. Instead of specifying a
           single value for the maximum number of pcs it is now possible
           to specify an array, e.g. c(3,5,7,9.20) or 3:7
12/11/06 - Added a cluster based imputation method called llsImpute.
           This is mainly thought for comparison with the other methods.
           kEstimate may also be used with llsImpute.
08/27/06 - This is the first revision of our pca package. Enjoy!
