mostly to get the NONE constant out of the global namespace, so I can
convert other enums which also want to use the NONE constant

Change-Id: I988d5d7e5316dd5e4ca0be0cc8f043f69bbb900c
Reviewed-on: https://gerrit.libreoffice.org/11848Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>