Save last-known FPlayer names

Instead of performing a lookup each time FPlayer#getName() is called,
save the player's name as s/he logs in

src/main/java/com/massivecraft/factions/listeners/FactionsPlayerListener.java

@@ -10,6 +10,7 @@ import com.massivecraft.factions.struct.Permission;
 import com.massivecraft.factions.struct.Relation;
 import com.massivecraft.factions.struct.Role;
 import com.massivecraft.factions.util.VisualizeUtil;
+import com.massivecraft.factions.zcore.persist.MemoryFPlayer;
 import com.massivecraft.factions.zcore.util.TL;
 import com.massivecraft.factions.zcore.util.TextUtil;
 import org.bukkit.Bukkit;
@@ -50,6 +51,7 @@ public class FactionsPlayerListener implements Listener {
     private void initPlayer(Player player) {
         // Make sure that all online players do have a fplayer.
         final FPlayer me = FPlayers.getInstance().getByPlayer(player);
+        ((MemoryFPlayer)me).setName(player.getName());
 
         // Update the lastLoginTime for this fplayer
         me.setLastLoginTime(System.currentTimeMillis());

src/main/java/com/massivecraft/factions/zcore/persist/MemoryFPlayer.java

@@ -65,6 +65,7 @@ public abstract class MemoryFPlayer implements FPlayer {
     protected ChatMode chatMode;
 
     protected String id;
+    protected String name;
 
     protected boolean monitorJoins;
 
@@ -333,11 +334,18 @@ public abstract class MemoryFPlayer implements FPlayer {
     }
 
     public String getName() {
-        if (isOnline()) {
-            return getPlayer().getName();
+        if (this.name == null) {
+            // Older versions of FactionsUUID don't save the name,
+            // so `name` will be null the first time it's retrieved
+            // after updating
+            OfflinePlayer offline = Bukkit.getOfflinePlayer(UUID.fromString(getId()));
+            this.name = offline.getName() != null ? offline.getName() : getId();
         }
-        OfflinePlayer player = Bukkit.getOfflinePlayer(UUID.fromString(getId()));
-        return player.getName() != null ? player.getName() : getId();
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
     }
 
     public String getTag() {
@@ -780,12 +788,7 @@ public abstract class MemoryFPlayer implements FPlayer {
     }
 
     public Player getPlayer() {
-        for (Player player : Bukkit.getServer().getOnlinePlayers()) {
-            if (player.getUniqueId().toString().equals(this.getId())) {
-                return player;
-            }
-        }
-        return null;
+        return Bukkit.getPlayer(UUID.fromString(this.getId()));
     }
 
     public boolean isOnline() {