Add Add [resource] in this tile Unique

[RobLoach]

This introduces two new uniques to add resources to tiles...

Add [resource] in this tile
[relativeAmount] [resourceFilter] resource in this tile

With these, you're able to add a resource to a tile, and even modify the amount that's represented there.

Examples

Add [Horses] in this tile
Add [Crabs] in this tile
[+5] [Horses] resource in this tile
[+5] [Strategic] resource in this tile // Will only increase a Strategic resource

Use Case

In the BNW mod, we need to make Antiquity Sites spawn from ancient ruins. With these new uniques, we can do...

{
	"name": "Ancient ruins",
	"terrainsCanBeBuiltOn": ["Land"],
	"uniques": [
		"Provides a random bonus when entered",
		"Add [Antiquity Site] in this tile"
	]
}

And that will ensure a Antiquity Site appears underneth the Ancient ruins, if possible.