Potential data loss: Nimsuggest should not run on .nims files

[mratsim]

See: nim-lang/nimsuggest#29

I have an exec "cp -r foo/ bar.$$/" statement ($$ means process PID in bash) and everytime I make a change, nimsuggest creates a new directory.

That means that if I start writing a "rm" statement and nimsuggest runs I can lose data.