Description: Function for Likelihood Ratio Based Confidence Intervals
References: Thomas D.R., Grunkemeier, G.L. (1975) "Confidence Interval Estimation of Survival Probabilities for Censored Data". Journal of the American Statistical Association, 70, 865 - 871. Li, G. (1995) "On nonparametric likelihood ratio estimation of survival probabilities for censored data". Statistics and Probability Letters, 25, 95 - 104.