Danubius village / fortress cleanup.

Don't clone, change and overwrite the gaul stone wallstyle but create two custom ones from scratch, refs r19434 / D204.
Move houses away from the gates following rP20626, so that gaia units can easily move in and out.
Replace spike template name copies from rP20626 with references.
Try to find a more transparent data structure, at least for the spikes.
Some whitespace changes.