add source in backup/restore failure message

introduced dependency to lgc > 0.47 for new stacklevel argument to deprecated + new db backup/restore api

handle lgc.adbh api changes within regards of backup/restore: * new backup_commands method instead of backup_command * some backend still return command as string as expected by os.system, not subprocess.call

match_rtype hook selector now accepts frometypes/toetypes optional arguments to match only given subject/object entity types

a selector MUST NO return None

some fixes so that deprecation warning are properly localized

to ease overriding of field.choices using *function* (set using autoform_field_kwargs), give the field as named argument

refactor attributes'value generator to deal with yams special Attribute/NOW/TODAY values that may be used on [Interval]BoundConstraint (BoundConstraint wasn't handled btw, fix this). Besides passing 'entity' to generate_* function (needed to get value for another attribute when computing one for instance): * set nicer method names and makes clearer what's private/protected/public * properly handle choices, constraints on float/date/datetime fields

backport stable

backport stable