[R-Forge #298] Create weekday integer class

[arunsrinivasan]

Submitted by: Matt Dowle; Assigned to: Nobody; R-Forge link

So that 20080104+1==20080107.

[jangorecki]

Adding example:

x = as.Date("2008-01-04")
y = as.Date("2008-01-07")
weekdays(c(x, y))
#[1] "Friday" "Monday"
x + 1 == y
#[1] FALSE

# weekday is a new class
x = as.weekday(x)
y = as.weekday(y)
x + 1 == y
#[1] TRUE

Before implementing worth to double check if we want to have it in data.table. There is a nice nanotime package that we could use to oursource all new date-time stuff.