Review StyleCop rules.

- Enforce SA1604 ElementDocumentationShouldHaveSummary.
- Enforce SA1629 DocumentationTextShouldEndWithAPeriod.
- Turn off some rules covered by IDExxxx rules.
- Remaining rules are treated as part of OpenRA style.

OpenRA.Mods.Common/UpdateRules/UpdateRule.cs

@@ -19,11 +19,11 @@ namespace OpenRA.Mods.Common.UpdateRules
 		public abstract string Description { get; }
 
 		/// <summary>Defines a transformation that is run on each top-level node in a yaml file set.</summary>
-		/// <returns>An enumerable of manual steps to be run by the user</returns>
+		/// <returns>An enumerable of manual steps to be run by the user.</returns>
 		public delegate IEnumerable<string> TopLevelNodeTransform(ModData modData, MiniYamlNode node);
 
 		/// <summary>Defines a transformation that is run on each widget node in a chrome yaml file set.</summary>
-		/// <returns>An enumerable of manual steps to be run by the user</returns>
+		/// <returns>An enumerable of manual steps to be run by the user.</returns>
 		public delegate IEnumerable<string> ChromeNodeTransform(ModData modData, MiniYamlNode widgetNode);
 
 		public virtual IEnumerable<string> UpdateActorNode(ModData modData, MiniYamlNode actorNode) { yield break; }