Fix typos

Found via `codespell -q 3 -L aci,addmin,ake,aline,alle,alledges,alocation,als,ang,anid,anormal,aply,apoints,ba,beginn,behaviour,bloaded,bottome,brushin,bu,byteorder,calculater,cancelled,cancelling,cas,cascade,centimetre,childrens,childs,colour,colours,commen,connexion,currenty,documentin,dof,doubleclick,dum,eiter,elemente,ende,feld,finde,findf,findn,fle,freez,graphin,hist,iff,incrementin,indexin,indicies,initialisation,initialise,initialised,initialises,initialisiert,inout,ist,itsel,kilometre,leadin,localy,lod,mantatory,methode,metres,millimetre,modell,nd,noe,normale,normaly,nto,numer,oce,oder,ontop,orgin,orginx,orginy,ot,pard,parm,parms,pres,programm,que,rady,recurrance,renderin,rin,ro,rougly,sectionin,seperator,serie,shs,sinc,siz,som,strack,substraction,te,technic,thist,thru,tread,tru,ue,uint,unter,uptodate,vas,vertexes,vew,wallthickness,whitespaces -S "./.git,*.po,*.ts,*.pdf,./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/Base/StackWalker.cpp,./build/doc/SourceDoc,./tools/build/WindowsInstaller/lang,./src/Mod/TechDraw/Templates/locale"`

src/Mod/Fem/App/FemPostPipeline.cpp

@@ -185,8 +185,8 @@ int FemFrameSourceAlgorithm::RequestData(vtkInformation*,
         auto time = outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_TIME_STEP());
         auto frames = getFrameValues();
 
-        // we have float values, so be aware of roundign erros. lets subtract the searched time and
-        // then use the smalles value
+        // we have float values, so be aware of rounding errors. lets subtract the searched time and
+        // then use the smallest value
         for (auto& frame : frames) {
             frame = std::abs(frame - time);
         }
@@ -257,7 +257,7 @@ bool FemPostPipeline::allowObject(App::DocumentObject* obj)
         return true;
     }
 
-    // and all standart Post objects the group can handle
+    // and all standard Post objects the group can handle
     return FemPostGroupExtension::allowObject(obj);
 }
 
@@ -360,7 +360,7 @@ void FemPostPipeline::scale(double s)
 
 App::DocumentObjectExecReturn* FemPostPipeline::execute()
 {
-    // we fake a recalculated data oject, so that the viewprovider updates
+    // we fake a recalculated data object, so that the viewprovider updates
     // the visualization. We do not want to do this in onChange, as it
     // could theoretically be long running
     if (m_data_updated) {
@@ -487,7 +487,7 @@ void FemPostPipeline::onChanged(const Property* prop)
             FemPostFilter* nextFilter = obj;
             nextFilter->getFilterInput()->RemoveAllInputConnections(0);
 
-            // handle input modes (Parallel is seperated, alll other settings are serial, just in
+            // handle input modes (Parallel is separated, all other settings are serial, just in
             // case an old document is loaded with "custom" mode, idx 2)
             if (Mode.getValue() == Fem::PostGroupMode::Parallel) {
                 // parallel: all filters get out input