Compatiblity patch for abandoned addons.

[Moderocky]

Description

Despite the legacy converters class being scheduled for removal several years ago, some addons have not removed code depending on it.
As this class is (was) removed in 2.10, these addons will fail to load unless they are recompiled.

Many addons are unaffected by this, since the alternative has been around for a long time.

Since this issue seemed quite widespread (based on a GitHub all-repositories search),
I have added a temporary 'patch' to make these addons load, using a stub of the removed class. The stub will print a large warning if an outdated addon tries to use the class, and a large amount of its (unsupported) functionality is no longer available, but it does mean that most outdated addons, e.g. skript-gui, will still load.

These stubs have the maximum amount of compile-time warnings and errors I can put on them, and they will be removed in future. This is not a permanent fix, just a temporary motivation for developers who have not updated their work in time.

Affected Classes

• ch.njol.skript.registrations.Converters
• ch.njol.skript.classes.Converter

Example Warning

(This will presumably be red on a colour-supporting terminal.)

[APickledWalrus]

Should be fine with the changes. I will do some further in-game testing as well.