Add configurable cost to remain peaceful.

[LlmDl]

Description:

---

New Nodes/Commands/ConfigOptions:

	WAR_SIEGE_TOWN_PEACEFULNESS_COST(
			"war.siege.money.town_peacefulness_daily_cost",
			"0.0",
			"",
			"# The cost that a town must pay to remain peaceful. Disabled when set to 0.0.",
			"# This cost is paid after a town pays their upkeep and has their days-to-peaceful-change counted.",
			"# If a town cannot pay the peaceful cost after they have their peaceful setting changed back to false."),

---

Relevant Issue ticket:

Closes #931.

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• I have tested this pull request for defects on a server.

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