[schema] Use TZDatetime for creation_date and modification_date No work has been done for form fields/widgets since creation_date / modification_date are by default not editable through the default UI. One may want to add such feature at some point. Time will be displayed as UTC, let the end-application decide otherwise by customizing the tzdatetime printer if desired. Closes #4848923

import ConfigParser
try:
    undo_actions = config.cfgfile_parser.get('MAIN', 'undo-support', False)
except ConfigParser.NoOptionError:
    pass # this conf. file was probably already migrated
else:
    config.global_set_option('undo-enabled', bool(undo_actions))