An undocumented feature can be enabled by environment variable

export SD_SHOW_NUMBERING_PAGE=1

so a paragraph numbering tab pages shows up.

Change-Id: I21b0c8f6dffefd09fa783f29d3280c955513ddd6
Reviewed-on: https://gerrit.libreoffice.org/4852Tested-by: Caolán McNamara <caolanm@redhat.com>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>