Improvements to events calendar

[tfwoodroofMCS]

• [ ] Add functionality to allow recurring events.
• [ ] Make event start and finish time increments 15 minutes (rather than 1).
• [ ] Change button text from ‘Close’ to ‘Cancel’ when creating & editing events.
• [ ] After editing an event by clicking 'Edit Event', the button to confirm and close also reads 'Edit Event'. Change this to ‘Save’.
• [ ] When in Swedish mode:
  • [ ] Words in the dark boxes are displayed in English: 'today', 'month', 'week', 'day', and the month names.
  • [ ] Issues with creating, editing and saving events reported 15/12, but seemed to have been resolved as of 18/12 - verify.