Set MAX_CHARACTERS to None by default
Set MAX_CHARACTERS to None by default

Co-authored-by: Jean-Etienne Castagnede <096b26bc572e2e72b552b144acf938590c173160@gmail.com>
makinacorpus/django-mapentity,makinacorpus/django-mapentity,makinacorpus/django-mapentity