Change Approve and Reject links to buttons

And remove some comments.
Merge ReviewController into ModerationController

And add unimplemented endpoints.
Connect JS buttons to Scala endpoints.
Merge 'FlagIllegal' and 'FlagCopyVio' into 'FlagInapt', evolve database.
Remove PAP.Undo.
Make delete button mostly work

And: Add more Post and PostState fields. Add HidePost payload.
Tweak CSS for deleted posts.
Rename a few functions.
Add JS 'Deleted' and 'Hidden' post states, plus include dates.
Take deletions into account when sorting posts.
Make ClearFlags work

And add RawPostAction.deletedAt/ById, and break out review2().
Update moderation page when clearing flags.
Don't show flag counts and details on discussion pages.
Hide 'Hide post + send PM' buttons, not implemented.