feature: add extensions for bulk reactions

this is not api-level bulk reactions (!)

src/Discord.Net.Core/Extensions/MessageExtensions.cs

@@ -1,3 +1,5 @@
+using System.Threading.Tasks;
+
 namespace Discord
 {
     /// <summary>
@@ -17,5 +19,57 @@ namespace Discord
             var channel = msg.Channel;
             return $"https://discordapp.com/channels/{(channel is IDMChannel ? "@me" : $"{(channel as ITextChannel).GuildId}")}/{channel.Id}/{msg.Id}";
         }
+
+        /// <summary>
+        ///     Add multiple reactions to a message.
+        /// </summary>
+        /// <remarks>
+        ///     This method does not bulk add reactions! It will send a request for each reaction inculded.
+        /// </remarks>
+        /// <example>
+        /// <code language="cs">
+        /// IEmote A = new Emoji("🅰");
+        /// IEmote B = new Emoji("🅱");
+        /// await msg.AddReactionsAsync(new[] { A, B });
+        /// </code>
+        /// </example>
+        /// <param name="msg">The message to add reactions to.</param>
+        /// <param name="reactions">An array of reactions to add to the message</param>
+        /// <param name="options">The options to be used when sending the request.</param>
+        /// <returns>
+        ///     A task that represents the asynchronous operation for adding a reaction to this message.
+        /// </returns>
+        /// <seealso cref="IUserMessage.AddReactionAsync(IEmote, RequestOptions)"/>
+        /// <seealso cref="IEmote"/>
+        public static async Task AddReactionsAsync(this IUserMessage msg, IEmote[] reactions, RequestOptions options = null)
+        {
+            foreach (var rxn in reactions)
+                await msg.AddReactionAsync(rxn, options).ConfigureAwait(false);
+        }
+        /// <summary>
+        ///     Remove multiple reactions from a message.
+        /// </summary>
+        /// <remarks>
+        ///     This method does not bulk remove reactions! If you want to clear reactions from a message,
+        ///     <see cref="IUserMessage.RemoveAllReactionsAsync(RequestOptions)"/>
+        /// </remarks>
+        /// <example>
+        /// <code language="cs">
+        /// await msg.RemoveReactionsAsync(currentUser, new[] { A, B });
+        /// </code>
+        /// </example>
+        /// <param name="msg">The message to remove reactions from.</param>
+        /// <param name="reactions">An array of reactions to remove from the message</param>
+        /// <param name="options">The options to be used when sending the request.</param>
+        /// <returns>
+        ///     A task that represents the asynchronous operation for removing a reaction to this message.
+        /// </returns>
+        /// <seealso cref="IUserMessage.RemoveReactionAsync(IEmote, IUser, RequestOptions)"/>
+        /// <seealso cref="IEmote"/>
+        public static async Task RemoveReactionsAsync(this IUserMessage msg, IUser user, IEmote[] reactions, RequestOptions options = null)
+        {
+            foreach (var rxn in reactions)
+                await msg.RemoveReactionAsync(rxn, user, options).ConfigureAwait(false);
+        }
     }
 }