Make all methods S3-methods for easier integration with other packages like disk.frame

[xiaodaigh]

I want to integrate maditr with disk.frame but for that I need the methods in maditr to be S3 compatible. E.g.

let = function(data, ....) {
  UseMethod("let")
}

let.default = function(data, # omitted) {
  # your original let function implementation here; omitted
}

then in disk.frame I can implement the let method

let.disk.frame <- function(data,...) {
  # implement it for disk.frame
}

which will enable large datasets that doesn't fit into ram to benefit from maditr.

[gdemin]

Ok, will be added in the next release.

[gdemin]

Added in version 0.6.3