Harptosian Calendar system

[LiamVII]

As a: player and server owner
I want: the calendar to reflect the universe within which the game is in
So that: I can play the game according to the in-universe calendar

[LiamVII]

Initial draft problem breakdown -

1. a method to convert the real-world date-time to the in-system date-time.
2. a method to map this date-time over the Harptosian calendar, considering it is non-Gregorian.

(scrapped 2a and 2b ideas - the scope of information we need is very small comparatively, we can calculate everything we need directly from ms since the epoch)

3. provide a uniform formatted output for this information - dedicated class/method