Found via `codespell -q 3 -S *.ts,thirdparty,./toonz/sources/common/twain -L appy,ba,chunck,datas,forse,inbetween,inly,inout,pevent,possibile,strack,upto,vertexes`
Follow-up to PR #4156Closes#4072
Revert hidden unicode commit made by git client
* Fix misc. source comment and doxygen typos in ./toonz/sources/toonzlib
Found via `codespell -q 3 -S *.ts,./thirdparty -L dum,inbetween,sinc,uint ./toonz/sources/toonzlib`