Start work on adding reaction support

src/structures/MessageReaction.js

@@ -0,0 +1,41 @@
+const Collection = require('../util/Collection');
+const parseEmoji = require('../util/ParseEmoji');
+
+/**
+ * Represents a reaction to a message
+ */
+class MessageReaction {
+  constructor(message, emoji, count) {
+    /**
+     * The message that this reaction refers to
+     * @type {Message}
+     */
+    this.message = message;
+    /**
+     * The emoji of this reaction, if this is a string it is a plain unicode emoji.
+     * @type {Emoji}
+     */
+    this.emoji = emoji;
+    /**
+     * The number of people that have given the same reaction.
+     * @type {number}
+     */
+    this.count = count || 0;
+    /**
+     * The users that have given this reaction, mapped by their ID.
+     * @type {Collection<string, User>}
+     */
+    this.users = new Collection();
+  }
+
+  /**
+   * If the client has given this reaction to a message, it is removed.
+   * @returns {Promise<MessageReaction>}
+   */
+  remove() {
+    const message = this.message;
+    return message.client.rest.methods.removeMessageReaction(message.channel.id, message.id, parseEmoji(this.emoji));
+  }
+}
+
+module.exports = MessageReaction;