remove uses of is_active, we don't use that
introduce UserProhfile, the new UserProfile. not much working yet.
add a handmade userprofile migration
make a few things work. it doesn't immediately crash anymore
make some more things work. change userprohfile to userprofile again
make most things work
make most tests work with the new usermodel
make is_external handle empty email adresses
remove obsolete code
wip. split this up.