Fixed an issue where the sceduler stops accepting new schedules after…

… restart / discovery (#42)

src/Daemon/NetDaemon.Daemon/Daemon/NetDaemonHost.cs

@@ -611,7 +611,7 @@ public async Task StopDaemonActivitiesAsync()
             _stateActions.Clear();
             _serviceCallFunctionList.Clear();
 
-            await _scheduler.Stop();
+            await _scheduler.Restart();
         }
 
         /// <inheritdoc/>

src/Daemon/NetDaemon.Daemon/Daemon/Scheduler.cs

@@ -28,7 +28,7 @@ public class Scheduler : IScheduler
         /// <summary>
         ///     Used to cancel all running tasks
         /// </summary>
-        private readonly CancellationTokenSource _cancelSource = new CancellationTokenSource();
+        private CancellationTokenSource _cancelSource = new CancellationTokenSource();
 
         private readonly ConcurrentDictionary<int, Task> _scheduledTasks
                     = new ConcurrentDictionary<int, Task>();
@@ -271,6 +271,16 @@ public async Task Stop()
                 throw new ApplicationException("Failed to cancel all tasks");
         }
 
+        /// <summary>
+        ///     Restarts the scheduler. 
+        ///     Existing schedules are cancelled and the scheduler remains usable.
+        /// </summary>
+        public async Task Restart()
+        {
+            await Stop();
+            _cancelSource = new CancellationTokenSource();
+        }
+
         private async Task SchedulerLoop()
         {
             try