Possible fix for issue #311

[fcortell]

Added ical-expander to help calendar get more info about timezones.

[fcortell]

Requested changes commited.

[davish]

Thank you @fcortell! Would you be able to add some unit tests to confirm that timezones are working as expected? Some tests that would be useful given issues that users have had in the past:

• Event in GMT, user in a non-UTC timezone (e.g. Americas/New_York)
• Instance of a Rrecurring event scheduled before daylight savings, after daylight savings
• Event in Americas/New_York, user in a UTC timezone or a UTC+1 timezone
• Event/user in Indian Standard Time (UTC+5:30)

These could be snapshot-based tests that live in src/calendars/parsing/ics.test.ts.