I'm a bit late on the scene, but here's what I've got from a TF2 Datamaps dump:
tf_logic_gasworks may be in the FGD, but isn't in the actual game (or at least it doesn't appear in a datamaps dump).
filter_tf_player_wearing_item may be in the FGD, but isn't in the actual game (or at least it doesn't appear in a datamaps dump).
tf_logic_holiday gained both HalloweenSetUsingSpells and Halloween2013TeleportToHell inputs, the former apparently after the initial Halloween update.
I've updated the TF2 Item Definitions List page. There are a total of 3 Spellbook items. They are:
1069 - Fancy Spellbook
1070 - Spellbook Magazine
5604 - Fireproof Secret Diary
For those of you who were adding spells to your maps: Does the game prompt you to equip a spellbook when you spawn? I have a feeling that's what filter_tf_player_wearing_item was originally intended to do... however, without looking at a decompile of helltower, I couldn't say what replaced it.