19188

Another iteration on the Starfield

Please adjust the path for the local cache file to an appropriate directory if the current directory won't do for all platforms. Thanks!

Changes:
      o makes the stars move again
      o deletes the (now hopefully redundant) FieldOfView class
      o allows UrlReader to cache the downloaded content in a local file (updating it
         automatically when the server indicates a newer time stamp)
      o fixes bad deletion in UrlReader (delete instead of delete[])
      o allows UrlReader to advertise curl-supported compression algorithms to the server