Fix minor consistencies & redundant impl

src/Discord.Net.Commands/Attributes/Preconditions/RequireUserPermissionAttribute.cs

@@ -54,9 +54,9 @@ namespace Discord.Commands
             if (GuildPermission.HasValue)
             {
                 if (guildUser == null)
-                    return Task.FromResult(PreconditionResult.FromError("Command must be used in a guild channel"));                
+                    return Task.FromResult(PreconditionResult.FromError("Command must be used in a guild channel."));                
                 if (!guildUser.GuildPermissions.Has(GuildPermission.Value))
-                    return Task.FromResult(PreconditionResult.FromError($"User requires guild permission {GuildPermission.Value}"));
+                    return Task.FromResult(PreconditionResult.FromError($"User requires guild permission {GuildPermission.Value}."));
             }
 
             if (ChannelPermission.HasValue)
@@ -68,7 +68,7 @@ namespace Discord.Commands
                     perms = ChannelPermissions.All(context.Channel);
 
                 if (!perms.Has(ChannelPermission.Value))
-                    return Task.FromResult(PreconditionResult.FromError($"User requires channel permission {ChannelPermission.Value}"));
+                    return Task.FromResult(PreconditionResult.FromError($"User requires channel permission {ChannelPermission.Value}."));
             }
 
             return Task.FromResult(PreconditionResult.FromSuccess());

src/Discord.Net.Rest/Entities/Users/RestGuildUser.cs

@@ -9,7 +9,7 @@ using Model = Discord.API.GuildMember;
 namespace Discord.Rest
 {
     [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
-    public class RestGuildUser : RestUser, IGuildUser, IUpdateable
+    public class RestGuildUser : RestUser, IGuildUser
     {
         private long? _joinedAtTicks;
         private ImmutableArray<ulong> _roleIds;

src/Discord.Net.WebSocket/Audio/AudioClient.cs

@@ -16,7 +16,7 @@ using System.Collections.Generic;
 namespace Discord.Audio
 {
     //TODO: Add audio reconnecting
-    internal partial class AudioClient : IAudioClient, IDisposable
+    internal partial class AudioClient : IAudioClient
     {
         internal struct StreamPair
         {