added checks for forms
added check function in Study and StudySubject to avoid repeating a regex inline
removed previous checks in which the regex was rewritten
now the used regex is the one defined in the given study
added tests and migrations
changed functions in tests/functions to adapt the tests

moved function to utils.py (future code will also need the midnight function) and added utils module

Issue #239 Removed get_details method and changed extend_context method to use Worker.get_by_user. Enhancement: now the superuser also shows a name in the upper right corner or its username if no full_name is available.

Fixes issue #237 and #232 (duplicate). Added file web/views/daily_planning.py with class TemplateDailyPlannerView