Add new practice exercise meetup

[jiegillet]

This is week 32 of 48in24.

This one was fun, mostly because Elm's Time module is completely useless here, so you'll need to research algorithms and actually think for a bit.

[ceddlyburge]

I didn't take the time to fully understand this, but it looks it does what it should. Send like it practices weird date stuff not then elm though :)

[jiegillet]

Thank you!
Yeah, this exercise would a lot faster with access to a date library, but I did find it quite fun to do anyway :)