0 knockback was glitchy; fixed

Also attempt to fix problem when riding mobs via MobRider where mob and player end up underground after knockback; seems unsuccessful. Seeing as pigs in vanilla CraftBukkit without MobRider don't have this problem, but _do_ have the problem along with all other mobs when MobRider is loaded, I'm not bothering with this one further for now.

src/com/wimbli/WorldBorder/BorderCheckTask.java

@@ -3,6 +3,7 @@ package com.wimbli.WorldBorder;
 import org.bukkit.ChatColor;
 import org.bukkit.Effect;
 import org.bukkit.entity.Entity;
+import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Player;
 import org.bukkit.Location;
 import org.bukkit.Server;
@@ -23,6 +24,10 @@ public class BorderCheckTask implements Runnable
 		if (server == null)
 			return;
 
+		// if knockback is set to 0, simply return
+		if (Config.KnockBack() == 0.0)
+			return;
+
 		Player[] players = server.getOnlinePlayers();
 
 		for (int i = 0; i < players.length; i++){
@@ -72,7 +77,7 @@ public class BorderCheckTask implements Runnable
 			Entity ride = player.getVehicle();
 			if (ride != null)
 			{	// vehicles need to be offset vertically and have velocity stopped
-				double vertOffset = ride.getLocation().getY() - loc.getY();
+				double vertOffset = (ride instanceof LivingEntity) ? 0 : ride.getLocation().getY() - loc.getY();
 				newLoc.setY(newLoc.getY() + vertOffset);
 				ride.setVelocity(new Vector(0, 0, 0));
 				ride.teleport(newLoc);

src/com/wimbli/WorldBorder/BorderData.java

@@ -134,10 +134,6 @@ public class BorderData
 
 	public Location correctedPosition(Location loc, boolean round)
 	{
-		// if knockback is set to 0, simply return
-		if (Config.KnockBack() == 0.0)
-			return loc;
-
 		// if this border has a shape override set, use it
 		if (shapeRound != null)
 			round = shapeRound.booleanValue();

src/com/wimbli/WorldBorder/WBListener.java

@@ -14,6 +14,10 @@ public class WBListener implements Listener
 	{
 		if (event.isCancelled()) return;
 
+		// if knockback is set to 0, simply return
+		if (Config.KnockBack() == 0.0)
+			return;
+
 		Location newLoc = BorderCheckTask.checkPlayer(event.getPlayer(), event.getTo(), true);
 		if (newLoc != null)
 			event.setTo(newLoc);