Merge pull request #22 from txiki31/4

Vers 4 : suppression § obsoletes, marquage des points à revoir
Add required Postgresql's extensions pg_trgm and unaccent
Merge pull request #23 from eguaj/4

Add required Postgresql's extensions pg_trgm and unaccent
feat(PHP): Document max_input_vars and max_file_uploads error messages (refs #4544)
Merge pull request #26 from eguaj/4

feat(PHP): Document max_input_vars and max_file_uploads error messages (refs #4544)
complete migration
Merge pull request #27 from Eric-Brison/4

complete migration