[1.0]Some signposts not readable

[Robsoie]

Hello,

I have noticed in Dredfell that several of signposts do nothing, i mean for the signposts that work you just move on it and the text is displayed.
But for most of the ones found in Drefell, there's nothing, you move on them and there's no text appearing.

I noticed the same problem in Reknor when you explore it to finally find Golbug and the portal to the far east, ran into a signpost or two that didn't showed any kind of text.

[evouga]

I think signposts are like lore -- the messages disappear if you already have them in your fortress library.