Remove PageRole.parentRole

And remove code that verifies that any parent page role is correct.
Implement loadCategoryTree().
Add CACHED_NUM_LIKES and CACHED_NUM_WRONGS columns

And a code evolution that syncs all DW1_PAGES columns with
DW1_PAGE_ACTIONS.
Add and remove indexes.
Have listChildPages lookup children of many parents

And support more sort orders.
Index date column, and change from PageSortOrder to PageOrderOffset.
Let listChildPages() consider the offset.