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.

src/main/java/org/bukkit/Minecart.java

@@ -0,0 +1,22 @@
+package org.bukkit;
+
+/**
+ * Represents a minecart entity.
+ * 
+ * @author sk89q
+ */
+public interface Minecart extends Vehicle {
+    /**
+     * Sets a minecart's damage.
+     * 
+     * @param damage over 40 to "kill" a minecart
+     */
+    public void setDamage(int damage);
+    
+    /**
+     * Gets a minecart's damage.
+     * 
+     * @param damage
+     */
+    public int getDamage();
+}