Don't emit a newline in autoview. (#1466)

The extra newline character makes it hard to use nu as part of an
external processing pipeline, since the extra character could taint the
results. For example:

```
$ nu -c 'echo test | xxd'
00000000: 7465 7374                                test
```

versus

```
nu -c 'echo test' | xxd
00000000: 7465 7374 0a                             test.
```

crates/nu-protocol/src/macros.rs

@@ -3,6 +3,15 @@
 /// Note: this exists to differentiate between intentional writing to stdout
 /// and stray printlns left by accident
 #[macro_export]
+macro_rules! out {
+    ($($tokens:tt)*) => { print!($($tokens)*) }
+}
+
+/// Outputs to standard out with a newline added
+///
+/// Note: this exists to differentiate between intentional writing to stdout
+/// and stray printlns left by accident
+#[macro_export]
 macro_rules! outln {
     ($($tokens:tt)*) => { println!($($tokens)*) }
 }