Renamed 30_adduser_rawdog to 31_adduser_rawdog, so 30_adduser_user runs before 31_adduser_rawdog, so user "user" becomes uid=1000 instead of uid=1001.
whonix_shared/usr/share/whonix/postinst.d/70_shared_folder: create group "vboxsf" and add user "user" to group "vboxsf" by default to ease setting up virtualbox shared folder
work on #29