Add feature tour #233
Description
Is your feature request related to a problem? Please describe.
Introduce all (hidden) features to new users.
Describe the solution you'd like
Use features tour, https://pub.dev/packages/features_tour, to highlight following features:
- After first time showing weight list: Show long press to edit/delete entry
- After 30days between first and last measurement, show double click on graph
After showing these hints once, set flag to prevent recalling. Allow resetting them from FAQ, just like onboarding screen.