Now it's no longer possible to manipulate TID hash from arbitrary location
For example, this prevents linking of destroyed object into the hash
TID member is still public but writing to it is limited to a few very specific cases like serialization and player traveling between levels
https://forum.zdoom.org/viewtopic.php?t=64476
I think these were the last two still missing it, all remaining uses of the global level variable are in code that doesn't get run through a level tick and are supposed to access the primary level.
There is one exception in ACS for a net arbitrator check.
Aside from this the bot_observer CVAR was also removed. This was never implemented properly and could stomp upon custom player settings.
This was always used with 'consoleplayer' which really is the only thing making sense here. But this is a part of the global state which should be avoided in play code.
In particular, this makes no real sense in case of secondary maps where it should always return false.
The Map loader may not access any global state at all - everything it can touch must be exchangable.
Furthermore, if we want to sandbox each level, there may be no direct access to any kind of global state whatsoever from the play code.
This also changes the action special interface to pass a Level parameter to the separate functions and makes a few other minor adjustments to the polyobject code.
This should later be done for everything else as well, but the map loader should really be free of global dependencies ASAP.
Also replace TThinkerIterator<AActor> with FThinkerIterator globally because this only adds pointless type checks - with all actor subclasses being scripted this class has become redundant.
This involves passing the level explicitly to many functions. What was done here may seem a bit excessive but at least it covers everything.
Most importantly, the global ActiveThinker pointer has been moved into FLevelLocals and is now getting tracked properly by the level without using dangerous assumptions about how the game organizes its data.
- disallow bool as a return value for direct native calls because it only sets the lowest 8 bits of the return register.
- changed return type for several functions from bool to int where the return type was the only thing blocking use as direct native call.
