Lightning floating timezone warning

For the longest time (because I'm lazy), everytime thunderbird+lightning would start it would show three dialog box warnings about Unknown timezones being treated as the "floating" timezone.

This is easily fixed (in the sense that the warnings don't show anymore, and, given the nature of the fix, likely in the sense that timezone handling is now correct).

1. Edit | Preferences | Advanced | Config Editor
2. Click on the "I'll be careful" button.
3. search for calendar.icaljs boolean value
4. Set the value to true.