add locked state for posts that are removed or deleted, with banner, hiding reply form

[plebeius-eth]

Posts that are removed or deleted cannot be replied to, and the UI should reflect this.

[plebeius-eth]

2490bc3
actually I think the reply form should stay, like on old reddit

[estebanabaroa]

interestingly reddit lets you comment on removed posts, but plebbit doesnt. we should probably show "This post is ${state}. You won't be able to comment." It shouldn't say "locked" if a post is deleted and not locked.

[plebeius-eth]

should be fixed now: 7f6f0dd