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/Gui/Selection.cpp

@@ -759,7 +759,7 @@ int SelectionSingleton::setPreselect(const char* pDocName, const char* pObjectNa
 
     if(DocName==pDocName && FeatName==pObjectName && SubName==pSubName) {
         // MovePreselect is likely going to slow down large scene rendering.
-        // Disable it fow now.
+        // Disable it for now.
 #if 0
         if(hx!=x || hy!=y || hz!=z) {
             hx = x;
@@ -2344,4 +2344,3 @@ PyObject *SelectionSingleton::sGetSelectionFromStack(PyObject * /*self*/, PyObje
         return Py::new_reference_to(list);
     } PY_CATCH;
 }
-