This not only matches its use in CON but seems to be used as a counter in most other places as well.
The main reason is to improve readability of CON to ZScript conversions.
All classes with no skill filter now need an explicit noskill declaration.
The only exception is inert sprites using DukeActor directly, these will never get filtered by skill.
As soon as default init for CON gets in this won't work right anymore - these must come last, not first.
This commit contains all the trivial cases with no inheritance concerns.
All Duke script code has been changed to use strings as sound names now, just like GZDoom these will be looked up at compile time.
Original Duke sound indices still exist but are now being managed as resource IDs, not sound engine indices anymore.
