message: Add extension methods for converting from unix time to DateTime (win)
diff: @@ -69,8 +69,8 @@ namespace TogglDesktop.ViewModels
  .ToDictionary(pair => pair.Key, pair => pair.Value))
  .ToPropertyEx(this, x => x.TimeEntryBlocks);
  blocksObservable.Select(blocks => GenerateGapTimeEntryBlocks(blocks.Values
  - .Where(v => Toggl.DateTimeFromUnix(v.Started).Date <= SelectedDate &&
  - Toggl.DateTimeFromUnix(v.Ended).Date >= SelectedDate).ToList(), SelectedScaleMode)).ToPropertyEx(this, x => x.GapTimeEntryBlocks);
  + .Where(v => v.StartTime().Date <= SelectedDate && v.EndTime().Date >= SelectedDate).ToList(), SelectedScaleMode))
  + .ToPropertyEx(this, x => x.GapTimeEntryBlocks);
  this.WhenAnyValue(x => x.TimeEntryBlocks)
  .Where(blocks => blocks != null && blocks.Any())
  @@ -149,7 +149,7 @@ namespace TogglDesktop.ViewModels
  {
  if (chunk.Events.Any())
  {
  - var start = Toggl.DateTimeFromUnix(chunk.Started);
  + var start = chunk.StartTime();
  var block = new ActivityBlock()
  {
  Offset = ConvertTimeIntervalToHeight(selectedDate, start, selectedScaleMode),
  @@ -201,7 +201,7 @@ namespace TogglDesktop.ViewModels
  {
  if (blocks.ContainsKey(entry.GUID)) continue;
  - var startTime = Toggl.DateTimeFromUnix(entry.Started);
  + var startTime = entry.StartTime();
  var ended = entry.GUID == runningEntry?.GUID
  ? TimelineUtils.ConvertOffsetToTime(currentTimeOffset - 1, selectedDate, TimelineConstants.ScaleModes[selectedScaleMode])
  : entry.Ended;
  @@ -295,15 +295,15 @@ namespace TogglDesktop.ViewModels
  {
  var gaps = new List<GapTimeEntryBlock>();
  timeEntries.Sort((te1,te2) => te1.Started.CompareTo(te2.Started));
  - ulong? prevEnd = null;
  + TimeEntryBlock lastTimeEntry = null;
  foreach (var entry in timeEntries)
  {
  - if (prevEnd != null && entry.Started > prevEnd.Value)
  + if (lastTimeEntry != null && entry.Started > lastTimeEntry.Ended)
  {
  - var start = Toggl.DateTimeFromUnix(prevEnd.Value+1);
  + var start = lastTimeEntry.EndTime().AddSeconds(-1);
  var block = new GapTimeEntryBlock((offset, height) => AddNewTimeEntry(offset, height, selectedScaleMode, start.Date))
  {
  - Height = ConvertTimeIntervalToHeight(start, Toggl.DateTimeFromUnix(entry.Started - 1), selectedScaleMode),
  + Height = ConvertTimeIntervalToHeight(start, entry.StartTime().AddSeconds(-1), selectedScaleMode),
  VerticalOffset =
  ConvertTimeIntervalToHeight(new DateTime(start.Year, start.Month, start.Day), start, selectedScaleMode),
  HorizontalOffset = 0
  @@ -311,7 +311,7 @@ namespace TogglDesktop.ViewModels
  if (block.Height > 10) // Don't display to small gaps not to obstruct the view
  gaps.Add(block);
  }
  - prevEnd = !prevEnd.HasValue || entry.Ended > prevEnd ? entry.Ended : prevEnd;
  + lastTimeEntry = lastTimeEntry == null || entry.Ended > lastTimeEntry.Ended ? entry : lastTimeEntry;
  }
  return gaps;
  