Allow for delay in staging before separation.

I can't remember if this has been brought up before, but the instantaneous staging using AutoStaging when the fuel runs out is problematic and can cause sub-optimal staging. Especially with SRB's, if you eject the stages using AutoStage the instant after they burn out, I've had multiple occasions where they impact the launch vehicle and cause major damage. However, if I manually stage them by waiting even just a half second, there is no issue. I believe this has to do with the change in acceleration as the additional thrust goes from full power to nothing, whereas on the real thing, there is a gradual reduction in thrust over several seconds to make a more smooth shutdown. To counter this, you should either have a forced 0.5 second delay before autostaging activates, or you need to have the option in AutoStaging to add a pre-staging delay in addition to the post-staging delay already present.