Create DB script: missing ';'
Create DB: remove ORDER BY clause from v_erreurs_sub

This way errors are listed in the order in which they were created, so
the message about 'partage non autorisé' which is more a warning than an
error is displayed after more important errors.
Insert data: added missing left join in insert familles

This caused rows having 'ecole' set to blank not to be inserted in the
familles table
Insert data: fix foreign key issue

When updating existing enfants, if degré was '' instead of null a
foreign key constraint error would be triggered
Setup script: add logging to file

Exclude log files from git
Setup script: improve logging
Remove obsolete comment
core: Set PDO default fetch mode to ASSOC