Feature Request: Filtered generated calendar events

[burnflare]

https://webuild.sg/cal is a fantastic resource.

It'll be even more useful to have custom generated ical calendars too based on URL params. Example:

• https://webuild.sg/cal?group=NUSHackers would create a calendar that only returns events hosted by NUS Hackers.
• https://webuild.sg/cal?lat=1.276778&lng=103.846397&radius=5 would create a calendar that only returns events in a 5km radius from Tanjong Pagar.

[burnflare]

cc: @jin