Path: fix various typos and superfluous whitespace

Found via `codespell -q 3 -L aci,ake,aline,alle,alledges,alocation,als,ang,anid,apoints,ba,beginn,behaviour,bloaded,bottome,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,inout,ist,kilometre,lod,mantatory,methode,metres,millimetre,modell,nd,noe,normale,normaly,nto,numer,oder,ontop,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/Path/PathScripts/post/nccad_post.py

@@ -53,7 +53,7 @@ TOOL_CHANGE = '''G77      ; Move to release position
 M10 O6.0 ; Stop spindle
 M01 Insert tool TOOL
 G76      ; Move to reference point to ensure correct coordinates after tool change
-M10 O6.1 ; Start spindel'''
+M10 O6.1 ; Start spindle'''
 
 
 # gCode finishing the program

src/Mod/Path/PathScripts/post/uccnc_post.py

@@ -80,7 +80,7 @@ G80
 # POSTAMBLE possible values:
 #    Multi line text with gcode. Postable gcode
 #    The postamble text will appear following the last operation.
-POSTAMBLE_DEFAULT = '''M05 (stop spindel)
+POSTAMBLE_DEFAULT = '''M05 (stop spindle)
 G17 (Default: XY-plane)
 G54 (Default: First coordinate system)
 G40 (Default: Cutter radius compensation none)