Status of async script loading

[TheDGOfficial]

The asynchronous script loading config entry seems to be hidden and has to be manually added to the config to make it work. But, trying on a fresh 1.16.5 server with Skript v2.5.3 using only example scripts, it currently gives this error:

[05:15:04 WARN]: Exception in thread "Thread-5" java.lang.IllegalStateException: PreScriptLoadEvent may only be triggered synchronously.
[05:15:04 WARN]:        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:599)
[05:15:04 WARN]:        at ch.njol.skript.ScriptLoader.lambda$4(ScriptLoader.java:397)
[05:15:04 WARN]:        at ch.njol.skript.ScriptLoader.loadScripts(ScriptLoader.java:420)
[05:15:04 WARN]:        at ch.njol.skript.ScriptLoader.lambda$3(ScriptLoader.java:337)
[05:15:04 WARN]:        at ch.njol.skript.ScriptLoader$AsyncLoaderThread.run(ScriptLoader.java:310)

Few things there:

• The "Thread-5" is not meaningful, it should be changed to something like "Skript async script loader" or such.

• Events should have correct async calls to super constructor. (Cause of error)

• Maybe re-add to the config with a warning in full caps that this may break things.

• The loader thread is currently started even when this config option is disabled (or non-existent), and loops while (true) forever (it uses queues, which uses LockSupport#park, so it is performance friendly, but an useless thread drains thread stack, still.), so this line should be changed to only start the thread when isAsync method returns true: https://github.com/SkriptLang/Skript/blob/master/src/main/java/ch/njol/skript/ScriptLoader.java#L299

[TPGamesNL]

See #3324

Maybe re-add to the config with a warning in full caps that this may break things.

It's still true that asynchronous loading may break stuff, due to #3453

[TPGamesNL]

#1780
More things:

• Log handler errors when reloading, due to Log handler system isn't thread safe #3453 and what's mentioned below
• Skript gives the message that the script was reloaded before the reloading is done and removes the RedirectingLogHandler, so if a player reloading a script, they won't see any of the errors (they might if they're lucky, it's a race condition), as those will go to console.