title: Unblock File from within .net 4 c#
body: <p>Is there a possibility to unblock a file that is downloaded from the internet from within a c# program. 
  Surfing the internet I have learned, that the information is written in an alternative stream of a (NTFS) file that contains the current zone information (value 3 is from the internet and is interpreted as blocked).</p>
  
  <p>Is there a managed possiblity to either clear or change the zone information (unblock) of a file or is there a managed copy function that copies the files without the zone information?
  If not, how can I do with PInvoke but without including a foreign assembly (I'm not allowed to do this in a current project).</p>