Miscellaneous
-  Moved generic definition of selected to stabs which is required
anyway (thus, stabs >= 0.5-0 is now required) 
-  load AML dataset (AML_Bullinger.rda) from package TH.data 
-  Updated references (for stability selection, confidence
intervals and constrained regression) 
-  fixed inst/CITATION 
-  Refer to news(package = "mboost") instead of to the NEWS file. 
Bug-fixes
-  Cross-validation was potentially wrong for CoxPH() models.
Users can now choose if they want the naive cross-validation or
the improved version by Verweij and van Houwelingen (1993);
(spotted by Holger Reulen ) 
-  Examples in \dontrun are now executable and all dependencies
are properly stated in DESCRIPTION