Found via `codespell -q 3 -S ./thirdparty,*.po,./DONORS.md -L ackward,ang,ans,ba,beng,cas,childs,childrens,dof,doubleclick,fave,findn,hist,inout,leapyear,lod,nd,numer,ois,ony,paket,seeked,sinc,switchs,te,uint`
* The harcoded 8 slots are no more and impose limits in the new extension system.
* New system is limitless, although it will impose small performance hit with a mutex.
* Use a token to request the instance binding.
**Warning**: Mono will most likely break as a result of this, will need to be modified to use the new system.
* Deprecates GDNative in favor of a simpler, lower level interface.
* New extension system allows registering core engine classes.
* Simple header interface in gdnative_interace.h
