More post invasion options.

One thing i've noticed about invading systems is that they automatically become your colony. This is good and all early game when you need more colonies, but the problem arises when in late game you don't want to colonize anymore. These invaded systems don't come with the choice of razing the system, so that means i have to endure displeasure from my population because of auto colonization. What i want is to be given a choice after a successful invasion.

Choose to keep the colony-population will remain but slowly leave unless you raise happiness up

Destroy colony (two options) 

• Kick the entire population out and all system improvements are destroyed and are reset back when it was pre colonized.
• Kill the entire population and destroy system improvement but the downside is that there's a chance it will cause disapproval to your empire (goes higher depending how big is your pacifist party)

Maybe somewhere down the research tree you could get an option to turn habitable planets into Ashes or Lava as a way of resource deprivation against your enemy.

ps. we also need more ways to keep citizens happy.