Improve Lua type documentation and bindings.

The ExtractEmmyLuaAPI utility command, invoked with `--emmy-lua-api`, produces a documentation file that is used by the [OpenRA Lua Language Extension](https://marketplace.visualstudio.com/items?itemName=openra.vscode-openra-lua) to provide documentation and type information is VSCode and VSCode compatible editors when editing the Lua scripts.

We improve the documentation and types produced by this utility in a few ways:
- Require descriptions to be provided for all items.
- Fix the type definitions of the base engine types (cpos, wpos, wangle, wdist, wvec, cvec) to match with the actual bindings on the C# side. Add some extra bindings for these types to increase their utility.
- Introduce ScriptEmmyTypeOverrideAttribute to allow the C# side of the bindings to provide a more specific type. The utility command now requires this to be used to avoid accidentally exporting poor type information.
- Fix a handful of scripts where the new type information revealed warnings.

The ability to ScriptEmmyTypeOverrideAttribute allows parameters and return types to provide a more specific type compared to the previous, weak, type definition. For example LuaValue mapped to `any`, LuaTable mapped to `table`, and LuaFunction mapped to `function`. These types are all non-specific. `any` can be anything, `table` is a table without known types for its keys or values, `function` is a function with an unknown signature.

Now, we can provide specific types. , e.g. instead of `table`, ReinforcementsGlobal.ReinforceWithTransport is able to specify `{ [1]: actor, [2]: actor[] }` - a table with keys 1 and 2, whose values are an actor, and a table of actors respectively. The callback functions in MapGlobal now have signatures, e.g. instead of `function` we have `fun(a: actor):boolean`. In UtilsGlobal, we also make use of generic types. These work in a similar fashion to generics in C#. These methods operate on collections, we can introduce a generic parameter named `T` for the type of the items in those collections. Now the return type and callback parameters can also use that generic type. This means the return type or callback functions operate on the same type as whatever type is in the collection you pass in. e.g. Utils.Do accepts a collection typed as `T[]` with a callback function invoked on each item typed as `fun(item: T)`. If you pass in actors, the callback operates on an actor. If you pass in strings, the callback operates on a string, etc.

Overall, these changes should result in an improved user experience for those editing OpenRA Lua scripts in a compatible IDE.

OpenRA.Game/WDist.cs

@@ -21,8 +21,10 @@ namespace OpenRA
 	/// <summary>
 	/// 1d world distance - 1024 units = 1 cell.
 	/// </summary>
-	public readonly struct WDist : IComparable, IComparable<WDist>, IEquatable<WDist>,
-		IScriptBindable, ILuaAdditionBinding, ILuaSubtractionBinding, ILuaEqualityBinding, ILuaTableBinding
+	public readonly struct WDist : IComparable, IComparable<WDist>, IEquatable<WDist>, IScriptBindable,
+		ILuaAdditionBinding, ILuaSubtractionBinding, ILuaEqualityBinding, ILuaUnaryMinusBinding,
+		ILuaMultiplicationBinding, ILuaDivisionBinding, ILuaLessThanBinding, ILuaLessThanOrEqualToBinding,
+		ILuaTableBinding, ILuaToStringBinding
 	{
 		public readonly int Length;
 		public long LengthSquared => (long)Length * Length;
@@ -137,6 +139,40 @@ namespace OpenRA
 			return a == b;
 		}
 
+		public LuaValue Minus(LuaRuntime runtime) => new LuaCustomClrObject(-this);
+
+		public LuaValue Multiply(LuaRuntime runtime, LuaValue left, LuaValue right)
+		{
+			if (!left.TryGetClrValue(out WDist a) || !right.TryGetClrValue(out int b))
+				throw new LuaException("Attempted to call WDist.Multiply(WDist, integer) with invalid arguments.");
+
+			return new LuaCustomClrObject(a * b);
+		}
+
+		public LuaValue Divide(LuaRuntime runtime, LuaValue left, LuaValue right)
+		{
+			if (!left.TryGetClrValue(out WDist a) || !right.TryGetClrValue(out int b))
+				throw new LuaException("Attempted to call WDist.Divide(WDist, integer) with invalid arguments.");
+
+			return new LuaCustomClrObject(a / b);
+		}
+
+		public LuaValue LessThan(LuaRuntime runtime, LuaValue left, LuaValue right)
+		{
+			if (!left.TryGetClrValue(out WDist a) || !right.TryGetClrValue(out WDist b))
+				throw new LuaException("Attempted to call WDist.LessThan(WDist, WDist) with invalid arguments.");
+
+			return a < b;
+		}
+
+		public LuaValue LessThanOrEqualTo(LuaRuntime runtime, LuaValue left, LuaValue right)
+		{
+			if (!left.TryGetClrValue(out WDist a) || !right.TryGetClrValue(out WDist b))
+				throw new LuaException("Attempted to call WDist.LessThanOrEqualTo(WDist, WDist) with invalid arguments.");
+
+			return a <= b;
+		}
+
 		public LuaValue this[LuaRuntime runtime, LuaValue key]
 		{
 			get
@@ -150,6 +186,9 @@ namespace OpenRA
 
 			set => throw new LuaException("WDist is read-only. Use WDist.New to create a new value");
 		}
+
+		public LuaValue ToString(LuaRuntime runtime) => ToString();
+
 		#endregion
 	}
 }