title: hide/show a part of events in fullcalendar
body: <p>I'm building a calendar-based web app with fullcalendar, which is for college students to use. There are some categories I've defined. e.g, sport, art, mind, etc... every event in the fullcalendar would be assigned to a category.</p>
  
  <p>What i want to do is: there're some checkboxes corresponding categories on the top of the calendar, and the user can check or uncheck some checkboxed to hide/show the related events</p>
  
  <p>how would I achieve this?</p>