svx: Translated the svdmodel.hxx from German to English

Change-Id: I98d5e1308f192c302a4db023044d9246eff3c320
Reviewed-on: https://gerrit.libreoffice.org/9320
Reviewed-by: Thomas Arnhold <thomas@arnhold.org>
Tested-by: Thomas Arnhold <thomas@arnhold.org>