General uncontroversial cleanup:

- Made private methods static where possible (runtime can elide checking the object for null).
- Declared attribute classes as sealed (allows reflection on attributes to complete faster).
- Moved some static cctor's into field initializers (static cctor's are slower than static field initializers).
- Made classes static if they contained only static methods (can't create instances of useless objects).
- Use inferable Exts.Lazy and not new Lazy<T>().
- Added required STAThread attribute to CrashDialog.
- Removed unused parameters in private methods.
- Added Serializable attribute to exceptions.
- Added parameter name in calls to ArgumentNullException.
- Use of as operator instead of is + cast.
- Changed (x as Foo).Bar anti-pattern into ((Foo)x).Bar. Results in sensible cast exceptions on error rather than null dereferences.
- Removed unused method in NullShader.

OpenRA.Game/Scripting/ScriptMemberWrapper.cs

@@ -51,7 +51,7 @@ namespace OpenRA.Scripting
 			if (!IsMethod)
 				throw new LuaException("Trying to invoke a ScriptMemberWrapper that isn't a method!");
 
-			var mi = Member as MethodInfo;
+			var mi = (MethodInfo)Member;
 			var pi = mi.GetParameters();
 
 			object[] clrArgs = new object[pi.Length];
@@ -71,7 +71,7 @@ namespace OpenRA.Scripting
 					throw new LuaException("Unable to convert parameter {0} to {1}".F(i, pi[i].ParameterType.Name));
 			}
 
-			var ret = (Member as MethodInfo).Invoke(Target, clrArgs);
+			var ret = (mi.Invoke(Target, clrArgs));
 			return ret.ToLuaValue(context);
 		}