hadley/dplyr — pull request #633 by matthieugomez (2014-09-26 18:14:48+00:00)
Title: unique names  in data.table manipulations

- solves issue #615
- proposes solution for bug when object in the global environment is called `dt` or `vars`.

````R
library(dplyr)
library(data.table)
DT <- as.data.table(mtcars)
dt <- 6
DT %>% filter(cyl==dt)
````
Solution is is only implemented for filter_.data.table and filter_.grouped_dt as I was not sure it was the right way to do it.