Added GameMode command.

By: EvilSeph <evilseph@gmail.com>

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

@@ -1,5 +1,8 @@
 package org.bukkit;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import org.bukkit.entity.HumanEntity;
 
 /**
@@ -9,10 +12,42 @@ public enum GameMode {
     /**
      * Creative mode may fly, build instantly, become invulnerable and create free items
      */
-    CREATIVE,
-    
+    CREATIVE(1),
+
     /**
      * Survival mode is the "normal" gameplay type, with no special features.
      */
-    SURVIVAL;
+    SURVIVAL(0);
+
+    private final int value;
+    private final static Map<Integer, GameMode> modes = new HashMap<Integer, GameMode>();
+
+    private GameMode(final int value) {
+        this.value = value;
+    }
+
+    /**
+     * Gets the mode value associated with this GameMode
+     *
+     * @return An integer value of this gamemode
+     */
+    public int getValue() {
+        return value;
+    }
+
+    /**
+     * Gets the GameMode represented by the specified value
+     *
+     * @param value Value to check
+     * @return Associative {@link GameMode} with the given value, or null if it doesn't exist
+     */
+    public static GameMode getByValue(final int value) {
+        return modes.get(value);
+    }
+
+    static {
+        for (GameMode mode : GameMode.values()) {
+            modes.put(mode.getValue(), mode);
+        }
+    }
 }