add the library of generator
move `library(plotrix)`
init Huang2004
add test data
bug fixed: substring_index
enhance efficiency of Rcpp Class
apply faster API
Use .Call instead
correct test scripts
add dependency of RPPGen
no sapply when computing s(obj)

speed up a tiny bit
clarify variable z

z should be zi
round up t at any digit, for simulation debugging

since in simulation it is unlikely to get same event time,
round up a little bit like at 3rd digit
clean trail whitespace; uniform to tab indentation

replace 2-space soft tab to real tab
Merge branch 'master' into speed_cpp
add benchmark file, work on Q.hat, R.hat