Add missing exports for reaction stuff

src/structures/MessageReaction.js

@@ -1,5 +1,6 @@
 const Collection = require('../util/Collection');
 const Emoji = require('./Emoji');
+const ReactionEmoji = require('./ReactionEmoji');
 
 /**
  * Represents a reaction to a message
@@ -88,52 +89,4 @@ class MessageReaction {
   }
 }
 
-/**
- * Represents a limited emoji set used for both custom and unicode emojis. Custom emojis
- * will use this class opposed to the Emoji class when the client doesn't know enough
- * information about them.
- */
-class ReactionEmoji {
-  constructor(reaction, name, id) {
-    /**
-     * The message reaction this emoji refers to
-     * @type {MessageReaction}
-     */
-    this.reaction = reaction;
-
-    /**
-     * The name of this reaction emoji.
-     * @type {string}
-     */
-    this.name = name;
-
-    /**
-     * The ID of this reaction emoji.
-     * @type {string}
-     */
-    this.id = id;
-  }
-
-  /**
-   * The identifier of this emoji, used for message reactions
-   * @readonly
-   * @type {string}
-   */
-  get identifier() {
-    if (this.id) return `${this.name}:${this.id}`;
-    return encodeURIComponent(this.name);
-  }
-
-  /**
-   * Creates the text required to form a graphical emoji on Discord.
-   * @example
-   * // send the emoji used in a reaction to the channel the reaction is part of
-   * reaction.message.channel.sendMessage(`The emoji used is ${reaction.emoji}`);
-   * @returns {string}
-   */
-  toString() {
-    return this.id ? `<:${this.name}:${this.id}>` : this.name;
-  }
-}
-
 module.exports = MessageReaction;