Implemented vehicle hooks (some changes will still be made).

src/main/java/org/bukkit/event/vehicle/VehicleCollisionEvent.java

@@ -0,0 +1,14 @@
+package org.bukkit.event.vehicle;
+
+import org.bukkit.Vehicle;
+
+/**
+ * Raised when a vehicle collides.
+ * 
+ * @author sk89q
+ */
+public class VehicleCollisionEvent extends VehicleEvent {
+    public VehicleCollisionEvent(Type type, Vehicle vehicle) {
+        super(type, vehicle);
+    }
+}