[R-pkgs] Survival 2.39

[Therneau, Terry M., Ph.D.]

A new version of the survival package has been released.  The biggest change is stronger 
support for multi-state models, which is an outgrowth of their increasing use in my own 
practice. Interested users are directed to the "time dependent covariates" vignette for 
discussion of the tmerge and survSplit functions, which are useful tools to build the 
requisite data sets, and to the "multi-state" vignette for model fits and plots.

Terry Therneau