Fix typos and misc. formatting [skip ci]

Found via `codespell -q 3 -L aci,ake,aline,alle,alledges,alocation,als,ang,anid,ba,beginn,behaviour,bloaded,byteorder,calculater,cancelled,cancelling,cas,cascade,centimetre,childs,colour,colours,commen,currenty,dof,doubleclick,dum,eiter,elemente,feld,freez,hist,iff,indicies,initialisation,initialise,initialised,initialises,initialisiert,ist,kilometre,lod,mantatory,methode,metres,millimetre,modell,nd,noe,normale,normaly,nto,numer,oder,orgin,orginx,orginy,ot,pard,pres,programm,que,recurrance,rougly,seperator,serie,sinc,strack,substraction,te,thist,thru,tread,uint,unter,vertexes,wallthickness,whitespaces -S ./.git,*.po,*.ts,./ChangeLog.txt,./src/3rdParty,./src/Mod/Assembly/App/opendcm,./src/CXX,./src/zipios++,./src/Base/swig*,./src/Mod/Robot/App/kdl_cp,./src/Mod/Import/App/SCL,./src/WindowsInstaller,./src/Doc/FreeCAD.uml`

src/App/Document.cpp

@@ -3758,7 +3758,7 @@ void Document::removeObject(const char* sName)
         return;
 
     if (pos->second->testStatus(ObjectStatus::PendingRecompute)) {
-        // TODO: shall we allow removal if there is active udno transaction?
+        // TODO: shall we allow removal if there is active undo transaction?
         FC_LOG("pending remove of " << sName << " after recomputing document " << getName());
         pos->second->setStatus(ObjectStatus::PendingRemove,true);
         return;