Mutable dynamic arrays, heaps, and simple union find data structures

[marzipankaiser]

For writing examples, I wanted to have some standard mutable data structures, currently:

• dynamic/resizable arrays
• min-heap (=> priority queue)
• union-find on integers

They all still need more documentation, testing and maybe some additional functions (I only implemented what I needed).

[jiribenes]

Looks good so far!
I had some time during the meeting, so I quickly wrote some observations. :)

[b-studios]

What happened to this PR, it looks really cool! :)

[marzipankaiser]

@b-studios Mostly I didn't get around to doing much here since. The code is tested as far as the tests here go (so not much), but should mostly work (TM).
I'd like to do some cleanup before merging (e.g. we do have doc-comments now...)

[marzipankaiser]

Rebased, cleaned up a bit. Should be fine, except not tested well and not documented in too much detail, either.

[marzipankaiser]

Rebased to check if the Valgrind-issues happen to be fixed by now.

[b-studios]

Bike shed, in the comment you write "remove" but the function is called deleteMin. Some languages also call this operation pop (and insert then push):

https://doc.rust-lang.org/std/collections/struct.BinaryHeap.html

[marzipankaiser]

I chose the names based on what https://en.wikipedia.org/wiki/Binary_heap calls the operations, but we can rename them - I don't have a strong opinion here.

[jiribenes]

🪤 It could be fun to take the unification benchmark from other/unify and try it with the union find from this PR.