New head parts should be marked not playable

[matashina]

In EasyNPC. Discussion here

[focustense]

I don't know if the Discord chat will be forever available, so...

The main reason to do this is because sometimes mod authors forget to do so, and in some cases - I believe when they forget to distribute meshes/morphs with their head parts or just choose not to - actually trying to select that head part in the racemenu screen will crash the game.

So, even if the original head part was marked as playable, we should remove that flag. Since it's a clone anyway, there's no benefit to leaving it playable.