Update UMLet to v15.0.0

[LittleHuba]

I had some time to update umlet-mini to the newer version 15.0.0. You can take a look at the used umlet-version here: https://github.com/LittleHuba/umlet-mini

I did a lot of cleanup of the commits to also help with future version upgrades.

Fixes #1353

[ggrossetie]

Thanks!
Would it be possible to open a pull request on https://github.com/yuzutech/umlet/tree/mini ?

[LittleHuba]

Sure can do!

But I'd hesitate to merge this on top of that branch because that will remove a lot of the benefits of my work. E.g. rebasing on a newer release would again be a huge pain.

So I'd propose moving the current mini branch to a different branch mini_14_3_0 and then cloning my branch into a new branch mini.

Also I'm going on holiday for the next two weeks so I can only do so afterwards.

[ggrossetie]

So I'd propose moving the current mini branch to a different branch mini_14_3_0 and then cloning my branch into a new branch mini.

I'm fine with that but I want to compare/diff the code from each branch.

[LittleHuba]

I had to move my work to a new repository that was forked from your local one. The changes are the exact same. The diff is huge as expected but here you go: yuzutech/umlet#1

[ggrossetie]

merged in #1456
Thanks for your great work 💪🏻