several installer fixes and improvements:

- fix bug that registry uninstaller settings of the previous version are not replaced when installing new version of the same series

- avoid explicit calls of the name "FreeCAD"

- update example code and description to MSVC 2017 and FreeCAD 0.19git

src/WindowsInstaller/include/init.nsh

@@ -130,7 +130,10 @@ Function .onInit
    ${endif} 
   ${next}
   
-  ${if} $OldVersionNumber > ${APP_SERIES_KEY}
+  # NSIS cannot handle numbers with leading zero, thus cut it off before comparing
+  StrCpy $1 $OldVersionNumber "" 1
+  StrCpy $2 ${APP_SERIES_KEY} "" 1
+  ${if} $1 > $2
    # store the version number and reformat it temporarily for the error message
    StrCpy $R0 $OldVersionNumber
    StrCpy $OldVersionNumber $R5