Add daemon mode support

src/main.rs

@@ -68,7 +68,17 @@ fn language_name(code: &str) -> Option<String> {
 
 /// Runs application with these settings
 #[rustfmt::skip]
-pub fn main() -> Result<(), Box<dyn std::error::Error>> {
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    #[cfg(all(unix, not(target_os = "redox")))]
+    match fork::daemon(true, true) {
+        Ok(fork::Fork::Child) => (),
+        Ok(fork::Fork::Parent(_child_pid)) => process::exit(0),
+        Err(err) => {
+            eprintln!("failed to daemonize: {:?}", err);
+            process::exit(1);
+        }
+    }
+	
     env_logger::Builder::from_env(env_logger::Env::default().default_filter_or("warn")).init();
 
     localize::localize();