Check for .Renviron file

[Benedict Witzenberger]

Check if .Renviron exists in Home:

if(!file.exists(user_renviron)) # check to see if the file already exists
  file.create(user_renviron)
file.edit(user_renviron) # open with another text editor if this fails

[Benedict Witzenberger]

Is included in 813016c