Close opened files.

DiscImageChef.Checksums/SHA1Context.cs

@@ -102,7 +102,9 @@ namespace DiscImageChef.Checksums
         public byte[] File(string filename)
         {
             FileStream fileStream = new FileStream(filename, FileMode.Open);
-            return _sha1Provider.ComputeHash(fileStream);
+            byte[] result = _sha1Provider.ComputeHash(fileStream);
+            fileStream.Close();
+            return result;
         }
 
         /// <summary>
@@ -121,6 +123,8 @@ namespace DiscImageChef.Checksums
                 sha1Output.Append(hash[i].ToString("x2"));
             }
 
+            fileStream.Close();
+
             return sha1Output.ToString();
         }