fix source comment typos [skip ci]

Found via  codespell v2.1.dev0
```
codespell -q 3 -L aci,ake,aline,alle,alledges,alocation,als,ang,anid,apoints,ba,beginn,behaviour,bloaded,byteorder,calculater,cancelled,cancelling,cas,cascade,centimetre,childs,colour,colours,commen,connexion,currenty,dof,doubleclick,dum,eiter,elemente,ende,feld,finde,findf,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,parms,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,./build/doc/SourceDocu
```

src/Mod/Part/App/Part2DObject.h

@@ -73,7 +73,7 @@ public:
       * indexes geometryIndex1 and geometryIndex2 specify the corresponding curves that intersect
       * the curve geometryIndex.
       *
-      * If intersection is found, the associated geometryIndex1 or geometryIndex2 retuns -1.
+      * If intersection is found, the associated geometryIndex1 or geometryIndex2 returns -1.
       */
     static bool seekTrimPoints(const std::vector<Geometry *> &geomlist,
                                int geometryIndex, const Base::Vector3d &point,