Add example data

[KennethATaylor]

Could use data from Dong, et al. paper and/or reproduce simulated data from Gaber, et al. paper.

[KennethATaylor]

bladder and bladder1 from survival package are set up well to use and are pretty familiar datasets. Used in some MCC-related papers (Ghosh & Lin 2000).

Other options:

• readmission data from frailtypack package