Add comparer for IfAttributes

[Paul-1379]

Add the ability to make comparisons directly in the ifAttribute like:

using BaseTool;
using UnityEngine;

public class MonoScript : MonoBehaviour 
{
    public int Number;
    [If("Number == 0")] public int OtherNumber;
}

or:

using BaseTool;
using UnityEngine;

public class MonoScript : MonoBehaviour 
{
    public enum MyEnum
    {
        A,
        B
    }
    public MyEnum Enum;
    [If("Enumr == MyEnum.A")] public int Number;
}