Fix ignoring Fridays in booking time calculation
Fix including Sundays in booking time calculation
Clean up the js code to make it more readable
Get rid of location/room when unticking inherit

 - When unticking inherits from parent, remove the location/room values and save the
   contribution without a place
 - When changing the location, remove the room associated to it as well
 - When changing the location, update the room drop-down list accordingly (or disables it)
 - fixes #1577