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/Activities/Enter.cs

@@ -41,14 +41,14 @@ namespace OpenRA.Mods.Common.Activities
 
 		/// <summary>
 		/// Called early in the activity tick to allow subclasses to update state.
-		/// Call Cancel(self, true) if it is no longer valid to enter
+		/// Call Cancel(self, true) if it is no longer valid to enter.
 		/// </summary>
 		protected virtual void TickInner(Actor self, in Target target, bool targetIsDeadOrHiddenActor) { }
 
 		/// <summary>
 		/// Called when the actor is ready to transition from approaching to entering the target actor.
 		/// Return true to start entering, or false to wait in the WaitingToEnter state.
-		/// Call Cancel(self, true) before returning false if it is no longer valid to enter
+		/// Call Cancel(self, true) before returning false if it is no longer valid to enter.
 		/// </summary>
 		protected virtual bool TryStartEnter(Actor self, Actor targetActor) { return true; }