Added minecart classes, vehicle class, and the ability to spawn minecarts. StorageMinecart needs a getInventory(), but that is waiting on the addition of inventory code.

By: sk89q <the.sk89q@gmail.com>

paper-api/src/main/java/org/bukkit/Vehicle.java

@@ -0,0 +1,37 @@
+package org.bukkit;
+
+/**
+ * Represents a vehicle entity.
+ * 
+ * @author sk89q
+ */
+public interface Vehicle extends Entity {
+    /**
+     * Gets the vehicle's velocity.
+     * 
+     * @return velocity vector
+     */
+    public Vector getVelocity();
+    
+    /**
+     * Sets the vehicle's velocity.
+     * 
+     * @param vel velocity vector
+     */
+    public void setVelocity(Vector vel);
+    
+    /**
+     * Gets the primary passenger of a vehicle. For vehicles that could have
+     * multiple passengers, this will only return the primary passenger.
+     * 
+     * @return a living entity
+     */
+    public LivingEntity getPassenger();
+    
+    /**
+     * Returns true if the vehicle has no passengers.
+     * 
+     * @return
+     */
+    public boolean isEmpty();
+}