fix playout time zone bugs (#60)

* fix time zone bugs with playout building

* more time zone fixes

ErsatzTV.Core/Scheduling/PlayoutBuilder.cs

@@ -106,7 +106,7 @@ namespace ErsatzTV.Core.Scheduling
             PlayoutAnchor startAnchor = FindStartAnchor(playout, playoutStart, sortedScheduleItems);
 
             // start at the previously-decided time
-            DateTimeOffset currentTime = startAnchor.NextStart;
+            DateTimeOffset currentTime = startAnchor.NextStartOffset.ToLocalTime();
             _logger.LogDebug(
                 "Starting playout {PlayoutId} for channel {ChannelNumber} - {ChannelName} at {StartTime}",
                 playout.Id,
@@ -277,7 +277,7 @@ namespace ErsatzTV.Core.Scheduling
             playout.ProgramScheduleAnchors = BuildProgramScheduleAnchors(playout, collectionEnumerators);
 
             // remove any items outside the desired range
-            playout.Items.RemoveAll(old => old.Finish < playoutStart || old.Start > playoutFinish);
+            playout.Items.RemoveAll(old => old.FinishOffset < playoutStart || old.StartOffset > playoutFinish);
 
             return playout;
         }
@@ -297,7 +297,7 @@ namespace ErsatzTV.Core.Scheduling
                             {
                                 NextScheduleItem = schedule,
                                 NextScheduleItemId = schedule.Id,
-                                NextStart = start.Date + schedule.StartTime.GetValueOrDefault()
+                                NextStart = (start - start.TimeOfDay).UtcDateTime + schedule.StartTime.GetValueOrDefault()
                             };
                         case StartType.Dynamic:
                         default:
@@ -305,7 +305,7 @@ namespace ErsatzTV.Core.Scheduling
                             {
                                 NextScheduleItem = schedule,
                                 NextScheduleItemId = schedule.Id,
-                                NextStart = start.Date
+                                NextStart = (start - start.TimeOfDay).UtcDateTime
                             };
                     }
                 });