Added graceful option to die (kill coordinator without killing shards)

src/NadekoBot/Services/ICoordinator.cs

@@ -7,7 +7,7 @@ namespace NadekoBot.Services
     public interface ICoordinator
     {
         bool RestartBot();
-        void Die();
+        void Die(bool graceful);
         bool RestartShard(int shardId);
         IList<ShardStatus> GetAllShardStatuses();
         int GetGuildCount();

src/NadekoBot/Services/Impl/RemoteGrpcCoordinator.cs

@@ -39,11 +39,11 @@ namespace NadekoBot.Services
             return true;
         }
 
-        public void Die()
+        public void Die(bool graceful)
         {
             _coordClient.Die(new DieRequest()
             {
-                Graceful = false
+                Graceful = graceful
             });
         }
 

src/NadekoBot/Services/Impl/SingleProcessCoordinator.cs

@@ -36,7 +36,7 @@ namespace NadekoBot.Services
             return true;
         }
 
-        public void Die()
+        public void Die(bool graceful = false)
         {
             Environment.Exit(5);
         }