Add getLoopHandle() for accessing the underlying loop

These resources or objects may then be attributed to a specific extension via instanceof or get_resource_type() in implementations.

Fixes #16.

src/Loop.php

@@ -222,6 +222,15 @@ final class Loop
         return self::get()->supports($feature);
     }
 
+    /**
+     * Get the underlying loop handle.
+     *
+     * @return null|object|resource The loop handle the event loop operates on. Null if there is none.
+     */
+    public static function getLoopHandle() {
+        return self::get()->getLoopHandle();
+    }
+
     /**
      * Disable construction as this is a static class.
      */

src/LoopDriver.php

@@ -151,4 +151,13 @@ interface LoopDriver
      * @return bool
      */
     public function supports($feature);
+
+    /**
+     * Get the underlying loop handle.
+     *
+     * Example: the uv_loop resource for libuv or the EvLoop object for libev or null for a native driver
+     *
+     * @return null|object|resource The loop handle the event loop operates on. Null if there is none.
+     */
+    public static function getLoopHandle();
 }