AssetIconAttribute on method not working because of a validation bug (fix included)

[zacx-z]

When applied to a parameterless method, logging "method should have no parameters" error. Figured it's the bug in the condition of validation. In GraphicSourceSelector.cs, line 108:

		private static bool IsSupportedParameters(Type[] parameterTypes)
		{
			return parameterTypes.Length != 0;
		}

should be

			return parameterTypes.Length == 0;

[gjroelofs]

Ran into this as well at a gamejam, cheers for the attached fix @zacx-z.