Added fix for all-day events and floating timezones
As a reminder, the latest version should be copied from here: https://script.google.com/d/1QeZFLSM1EkuFvYcryECI_xH-IZVe1-IxGRq_n6OoXp1CmVtSeTeigEx4/edit?usp=sharing
This version includes the following fixes:
- All-day events where the start date is the same as the end date is technically against the ICS/ICAL standard, but we've seen it happen enough recently that we decided to account for it. More info can be found here: #57
- Fixed a timezone issue caused by events not having a timezone specified. More info can be found here: #34 (comment)