Add the feature of composing functions

[renkun-ken]

Composing functions should be allowed.

logdiff <- log %>% diff
lgplot <- log %>% diff %>% plot(col="red")
lgplot2 <- (function(x) x^2) %>% log %>% diff %>>% plot(.,col="red")

[renkun-ken]

No need to compose functions in this way, just use a function definition to store a common piping procedure.

procedure1 <- function(data) {
  data %>% log %>% diff %>% plot(col="red")
}