A few more tiles are needed

[bojidar-bg]

While doing a level for testing the new pathfinder (which is still not in git, but, well...), I think it would be nice if we have a bit more tiles:

1. Broken versions of the unwalkable and unbuildable tiles. (e.g. broken statues, pillars, etc.)
2. More Grass-Dirt transitions.
3. Some way to make good-looking castle walls (and optionally, village/city walls)
   • Maybe based off the current pillar tile, just vertical, plus some additional tiles for the corners.
   • Another idea would be to make it based on the buildable stone tiles.
   • A third idea would be to just make it look like a quickly done wall from sticks/spears/lances, i.e. https://en.wikipedia.org/wiki/Palisade
4. Umm.. what 4? That's all I can think of...