Minor: Map generator bug: Pillar generated too close to cave

[mdsanta]

Generated pillar is blocking exit for the player, who is riding, because bounce box of the horse doesn't fit in the remaining space.
Exit on foot or with the horse on leash is not an issue.

[jorb]

Also reported here. Made a note for future iterations of the map generator, but you could also just pick-axe it, I believe.