Hidden boards implemented

Builder/IISMainHandler/build.txt

@@ -1 +1 @@
-854
+856

Common/dataobjects/Board.cs

@@ -163,6 +163,7 @@ namespace FLocal.Common.dataobjects {
 						}
 					)
 					let board = Board.LoadById(id)
+					where board.sortOrder >= 0
 					orderby board.sortOrder, board.id
 					select board;
 			}

Common/dataobjects/Category.cs

@@ -90,6 +90,7 @@ namespace FLocal.Common.dataobjects {
 						}
 					)
 					let board = Board.LoadById(id)
+					where board.sortOrder >= 0
 					orderby board.sortOrder, board.id
 					select board;
 			}