Add lint check for invalid projectile angles

Emits error if
- angle exceeds 255 or -255
- minimum launch angle exceeds maximum launch angle

OpenRA.Game/WAngle.cs

@@ -19,6 +19,7 @@ namespace OpenRA
 	public struct WAngle : IEquatable<WAngle>
 	{
 		public readonly int Angle;
+		public int AngleSquared { get { return (int)Angle * Angle; } }
 
 		public WAngle(int a)
 		{