New functions bizdayseq, bizyears and bizyearseq

[wilsonfreitas]

The calendar object should hold the days-in-base value to compute the period in years.
And bizdayseq is a short cut to current days equivalence.

bizdayseq <- function(dates, curd) {
    dates <- as.Date(dates)
    bizdays(dates, dates+curd)
}

bizyears <- function(from, to) bizdays(from, to)/252

bizyearseq <- function(dates, curd) bizdayseq(dates, curd)/252

[wilsonfreitas]

All functions implemented.