Added support for Left 4 Dead and Left 4 Dead 2

examples/l4d.rs

@@ -0,0 +1,10 @@
+
+use gamedig::games::l4d;
+
+fn main() {
+    let response = l4d::query("207.246.72.170", Some(26999));
+    match response {
+        Err(error) => println!("Couldn't query, error: {error}"),
+        Ok(r) => println!("{:?}", r)
+    }
+}

examples/l4d2.rs

@@ -0,0 +1,10 @@
+
+use gamedig::games::l4d2;
+
+fn main() {
+    let response = l4d2::query("74.91.124.246", None);
+    match response {
+        Err(error) => println!("Couldn't query, error: {error}"),
+        Ok(r) => println!("{:?}", r)
+    }
+}