Groups and Containers: Don't bubble kill, revive, exists, active, visible, and alive down to members

Calling kill() or revive() on any group kills() or revives each member, but killing a group would have the same effect as killing the members since the group doesn't update or draw. This is espcially true for containers, and my most hated feature of FlxSpriteGroup/Containers is that setting exists sets exists all the way down. killing the group hides all members, but if a group had killed members when it was killed, reviving it should not revive those members.

I wanna lock this new behavior behind an optional compile flag, where a warning is given if they do set the flag or the counter-flag for their project. eventually we will warn for the counter-flag before removing the option

Start by reading FlxSpriteGroup and container behavior for kill, revive, exists, active, visible, and alive. Trace how the project handles compile flags and warnings. Done means the new non-bubbling behavior, preservation of independently killed members, and compatibility warnings for both flag choices are defined and covered.