[FIX] mute logger in some tests
[FIX] module loading: do not warn about missing access rules for AbstractModels
merge upstream
[IMP] trml2pdf: like css, invalid style name is not a warning.
[FIX] base: test_translation: load an existing translation
[FIX] html_sanitize: handle the case of empty documents (after sanitization).
[IMP] test_mail: do not mute logger
merge upstream
[MERGE] remove warnings