Reservation admin: some small improvements

The reservation form for administrator has been slightly improved in its ergonomics:

• Display of colored dots intended to differentiate users according to the subscription and the profile (the left dot corresponds to the subscription, the right one corresponds to the profile). Move the mouse over the dots for more details.
• It is no longer necessary to check "Repeat on other schedules", the list of courts is automatically displayed.
• In "Repeat every week", the scrolling box is now higher and allows to display up to 12 weeks at a time.
• List of labels : display of 30 labels instead of 10 before.