Prevent VehicleEnterEvent being sent when player exits vehicle.

Fix for BUKKIT-223.

Issue BUKKIT-223: When a player exits a minecart or boat, both a
VehicleExitEvent and a VehicleEnterEvent are fired.  Only the
VehicleExitEvent should fire.

Reason for bug: This occurs because the VehicleEnterEvent is fired in
EntityBoat.b and EntityMinecart.b *any* time a player right-clicks on
a vehicle, whether the right-click is to enter the vehicle or exit it.

Fix: By moving the creation of VehicleEnterEvents from EntityBoat.b
and EntityMinecart.b to Entity.setPassengerOf, we can create either a
VehicleEnterEvent or a VehicleExitEvent, depending on whether the
player is entering or exiting a vehicle.

src/main/java/net/minecraft/server/Entity.java

@@ -14,6 +14,7 @@ import org.bukkit.event.entity.EntityCombustByBlockEvent;
 import org.bukkit.event.entity.EntityCombustByEntityEvent;
 import org.bukkit.event.painting.PaintingBreakByEntityEvent;
 import org.bukkit.event.vehicle.VehicleBlockCollisionEvent;
+import org.bukkit.event.vehicle.VehicleEnterEvent;
 import org.bukkit.event.vehicle.VehicleExitEvent;
 import org.bukkit.craftbukkit.entity.CraftPlayer;
 import org.bukkit.event.entity.EntityCombustEvent;
@@ -1228,6 +1229,17 @@ public abstract class Entity {
             this.vehicle = null;
             this.setPositionRotation(entity.locX, entity.boundingBox.b + (double) entity.length, entity.locZ, this.yaw, this.pitch);
         } else {
+            // CraftBukkit start
+            if ((this.getBukkitEntity() instanceof LivingEntity) && (entity != null) && (entity.getBukkitEntity() instanceof Vehicle)) {
+                VehicleEnterEvent event = new VehicleEnterEvent((Vehicle) entity.getBukkitEntity(), (LivingEntity) this.getBukkitEntity());
+                this.world.getServer().getPluginManager().callEvent(event);
+                
+                if (event.isCancelled()) {
+                    return;
+                }
+            }
+            // CraftBukkit end
+
             if (this.vehicle != null) {
                 this.vehicle.passenger = null;
             }

src/main/java/net/minecraft/server/EntityBoat.java

@@ -420,15 +420,6 @@ public class EntityBoat extends Entity {
             return true;
         } else {
             if (!this.world.isStatic) {
-                // CraftBukkit start
-                VehicleEnterEvent event = new VehicleEnterEvent((Vehicle) this.getBukkitEntity(), entityhuman.getBukkitEntity());
-                this.world.getServer().getPluginManager().callEvent(event);
-
-                if (event.isCancelled()) {
-                    return true;
-                }
-                // CraftBukkit end
-
                 entityhuman.mount(this);
             }
 

src/main/java/net/minecraft/server/EntityMinecart.java

@@ -725,15 +725,8 @@ public class EntityMinecart extends Entity implements IInventory {
                 }
 
                 if (entity instanceof EntityLiving && !(entity instanceof EntityHuman) && this.type == 0 && this.motX * this.motX + this.motZ * this.motZ > 0.01D && this.passenger == null && entity.vehicle == null) {
-                    if (!collisionEvent.isPickupCancelled()) {
-                        VehicleEnterEvent enterEvent = new VehicleEnterEvent(vehicle, hitEntity);
-                        this.world.getServer().getPluginManager().callEvent(enterEvent);
-
-                        if (!enterEvent.isCancelled()) {
                     entity.mount(this);
                 }
-                    }
-                }
                 // CraftBukkit end
 
                 double d0 = entity.locX - this.locX;
@@ -857,17 +850,6 @@ public class EntityMinecart extends Entity implements IInventory {
             }
 
             if (!this.world.isStatic) {
-                // CraftBukkit start
-                org.bukkit.entity.Entity player = (entityhuman == null) ? null : entityhuman.getBukkitEntity();
-
-                VehicleEnterEvent event = new VehicleEnterEvent((Vehicle) this.getBukkitEntity(), player);
-                this.world.getServer().getPluginManager().callEvent(event);
-
-                if (event.isCancelled()) {
-                    return true;
-                }
-                // CraftBukkit end
-
                 entityhuman.mount(this);
             }
         } else if (this.type == 1) {