Consider translating top-level echo as print/println

Printing with echo:
```sh
echo -n foo
echo bar
```

Gets translated as (which works correctly):
```clj
(shell "echo" "-n" "foo")
(shell "echo" "bar")
```

We could make the output for top-level echos (that are not part of a pipeline) a bit nicer and idiomatic if we translate them as:
```clj
(print "foo")
(println "bar")
```
