Add cat demonstration program

Signed-off-by: Leni Aniva <v@leni.sh>

Author: lenianiva

Diff for: examples/cat.rs

@@ -0,0 +1,14 @@
+use rexpect::error::Error;
+use rexpect::spawn;
+
+fn main() -> Result<(), Error> {
+	let mut p = spawn("cat", Some(1000))?;
+
+	let ex: String = "∀".to_string();
+	p.send_line(&ex)?;
+	let line = p.read_line()?;
+
+	println!("In: {}", &ex);
+	println!("Out: {}", &line);
+	Ok(())
+}