Add IsBotModerator method

Very similar to a previously existing method that was mistakenly removed.

BirthdayBot.cs

@@ -120,8 +120,7 @@ namespace BirthdayBot
                 var gconf = await GuildConfiguration.LoadAsync(channel.Guild.Id);
 
                 // Ban check
-                bool isMod = gconf.ModeratorRole.HasValue && author.Roles.Any(r => r.Id == gconf.ModeratorRole.Value);
+                if (!gconf.IsBotModerator(author)) // skip check if user is a moderator
-                if (!isMod) // skip check if user is a moderator
                 {
                     if (await gconf.IsUserBlockedAsync(author.Id)) return; // silently ignore
                 }

Data/GuildConfiguration.cs

@@ -1,7 +1,9 @@
-using Npgsql;
+using Discord.WebSocket;
+using Npgsql;
 using NpgsqlTypes;
 using System;
 using System.Data.Common;
+using System.Linq;
 using System.Threading.Tasks;
 
 namespace BirthdayBot.Data
@@ -128,6 +130,13 @@ namespace BirthdayBot.Data
             return result != 0;
         }
 
+        /// <summary>
+        /// Checks if the given user can be considered a bot moderator.
+        /// Checks for either the Manage Guild permission or if the user is within a predetermined role.
+        /// </summary>
+        public bool IsBotModerator(SocketGuildUser user)
+            => user.GuildPermissions.ManageGuild || (ModeratorRole.HasValue && user.Roles.Any(r => r.Id == ModeratorRole.Value));
+
         #region Database
         public const string BackingTable = "settings";
         public const string BackingTableBans = "banned_users";