Cyclic should only emit a newline when writing to a TTY

Otherwise this messes up prototyping on the command line.

## New

```
$ cyclic 10
aaaabaaaca
$ cyclic 10 | phd
00000000  61 61 61 61  62 61 61 61  63 61                     │aaaa│baaa│ca│
0000000a
```

## Old

```
$ cyclic 10 | phd
00000000  61 61 61 61  62 61 61 61  63 61 0a                  │aaaa│baaa│ca⋅│
0000000b
```