Updated TimeZoneInfoTest.DSTTransisions to correct .NET behavior.
Test TimeZoneInfo.GetUtcOffset with multiple DST and DateTimeKind.
Simplified TimeZone.ToLocalTime.
Old code was producing invalid DST dates.
ConvertTimeToUtc no longer relies in DateTime.ToUniversalTime.
Removed repeated logic from TimeZoneInfo.ConvertTimeToUtc.
Created helper method TimeZoneInfo.IsInDST.
TimeZoneInfo.GetUtcOffset now handles all DateTimeKinds.
Removed GetUtcOffset cohesion with TimeZoneInfo.IsDaylightSavingTime.
TimeZoneInfo.IsDaylightSavingTime now uses GetUtcOffset.