Write standard input message to standard error

Resolves Issue #43

src/arguments/mod.rs

@@ -362,7 +362,11 @@ fn quote_inputs(input: &str) -> String {
 fn write_stdin_to_disk(max_args: usize, mut unprocessed_path: PathBuf, inputs_are_commands: bool,
     quote_enabled: bool) -> Result<usize, ParseErr>
 {
-    println!("parallel: reading inputs from standard input");
+    // Write a message to standard error that inputs are being read from standard input
+    let stderr = io::stderr();
+    let mut stderr = stderr.lock();
+    let _ = stderr.write(b"parallel: reading inputs from standard input\n");
+
     unprocessed_path.push("unprocessed");
     let disk_buffer = fs::OpenOptions::new().truncate(true).write(true).create(true).open(&unprocessed_path)
         .map_err(|why| ParseErr::File(FileErr::Open(unprocessed_path.clone(), why)))?;

src/tokenizer/functions.rs

@@ -31,6 +31,7 @@ pub fn dirname(input: &str) -> &str {
 #[cfg(test)]
 mod tests {
     use super::*;
+
     #[test]
     fn path_remove_ext_simple() {
         assert_eq!(remove_extension("foo.txt"), "foo");