Fix typos [skip-ci]

Found via codespell v1.17.0.dev0  
``` 
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,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,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/Mod/Arch/OfflineRenderingUtils.py

@@ -753,7 +753,7 @@ def buildGuiDocumentFromGuiData(document,guidata):
                 # then rest of bytes represent colors value where each color
                 # is of 4 bytes in abgr order.
 
-                # convert number of colors into hexadecimal reprsentation
+                # convert number of colors into hexadecimal representation
                 hex_repr = hex(len(prop["value"]))[2:]
 
                 # if len of `hex_repr` is odd, then add 0 padding.