Added a trait that removes an actor when prereqs are met, with delay.

It is quite useful if you want a switch upgrade.
An example would be to upgrade rifleman to use bazookas, that unlocks an upgrade to revert them back to rifles, when that is researched it kills the actor that had the other prereqs so you don`t have both at once.

Its also quite funny to see all your powerplants explode when you build a barracks.
If you have a property ```public int ticks;``` and someone wants to attach a display bar to this, they can also find and display the remaining ticks (i.e. show how much lifetime the actor has left).
So it might be better to locally keep track of this ```info.Delay``` before removal occurs. Again ```ITick``` would be needed.