Most of the custom logic to handle special keying cases is now inside
the AnimationPlayerEditorPlugin.
The EditorInspector now emits a signal when inspecting a new object.
Found via `codespell -q 3 -S ./thirdparty,*.po,./DONORS.md -L ackward,ang,ans,ba,beng,cas,childs,childrens,dof,doubleclick,expct,fave,findn,gird,hist,inh,inout,leapyear,lod,nd,numer,ois,ony,paket,ro,seeked,sinc,switchs,te,uint,varn,vew`
Primary and secondary handles are no longer differentiated by their ids, so a bool was added to tell them apart in all the handle-related methods.
Includes a minor fix in CollisionPolygon3DEditor, unrelated to editor gizmos.
Using codespell 2.1.0.
Method:
```
$ cat > ../godot-word-whitelist.txt << EOF
ang
ans
ba
curvelinear
dof
doubleclick
fave
findn
gird
inout
leapyear
lod
merchantibility
nd
numer
ois
ony
que
readded
seeked
statics