SSE deadlines countdown

Based on sec-deadlines by @bogdan-kulynych which is based on ai-deadlines by @abhshkdz

Adding/updating a conference

• Read the data format description below. Note that the timezone format sign is inverted (e.g., UTC+7 is written as Etc/GMT-7). It's not a bug. I hate this format too. I'd be happy to move to a different timezone JavaScript library that uses a friendlier format, but I don't have time for that.
• Update _data/conferences.yml. You can do that on Github or locally after forking the repo.
• Send a pull request

Conference entry record

Example record:

- name: ICSE
  description: International Conference on Software Engineering
  year: 2021
  link: https://conf.researchr.org/home/icse-2021
  deadline: "2020-10-18 23:59"
  date: May 22–25
  place: Madrid ES
  tags: [SE]

Descriptions of the fields:

Field name	Description
name*	Short conference name, without year
description	Description, or long name
year*	Year the conference is happening
link*	URL to the conference home page
deadline*	Deadline, or list of deadlines. "TBA" if not announced. (details below)
timezone	Timezone in tz format. By default is UTC-12 (AoE)
comment	Additional info on the deadline, e.g. a separate Abstract deadline
date	When the conference is happening
place	Where the conference is happening
tags	One or multiple tags: SE, TEST, SEC, PRIV, or AUTO

Fields marked with asterisk (*) are required.

Deadline format

The deadline field can contain:

1. The simplest option: a date and time in ISO format. Example: "2017-08-19 23:59".
2. If a deadline is rolling, you can use a template date, just substitute the year with %y. Example: "%y-04-15 23:59" means there is a deadline on the 15th of April every year.
3. A list of (1) or (2). Example of two rolling deadlines, with one in the end of May every year, and the second in the end of February:

- "%y-05-31 23:59"
- "%y-02-28 23:59"

On the page, all deadlines are displayed in viewer's local time (that's a feature).

Note: If the deadline hour is {h}:00, it will be automatically translated into {h-1}:59:59 to avoid pain and confusion when it happens to be midnight in local time.

Timezones

The timezone is specified in tz format. Unlike abbreviations (e.g. EST), these are un-ambiguous. Here are tz codes for some common timezones:

Common name	tz
UTC	Etc/UTC
America Pacific Time	America/Los_Angeles
Pacific Standard Time (UTC-8)	Etc/GMT+8 (Yes, the sign is inverted for some weird reason)
America Eastern Time	America/New_York
Eastern Standard Time (UTC-5)	Etc/GMT+5
American Samoa Time (UTC-11)	Pacific/Samoa or Etc/GMT+11. This timezone does not use DST.
Aleutian Islands	America/Adak