Shorter HLD

[kth-competitive-programming]

Shorter HLD

[Chillee]

I propose we remove KACTL's for Benq's (https://github.com/bqi343/USACO/blob/master/Implementations/content/graphs%20(12)/Trees%20(10)/HLD%20(10.3).h). I know we've had discussions about removing it entirely, but I think there's value in having the more straightforward one around (that more people understand).

There's also the matter of the subtree modifications trick: https://codeforces.com/blog/entry/53170

The same can be done with LCT's, but I think that's messy. There's also another data structure called AAA-trees (also called self adjusting top trees) that supports subtree/path modification/query but that's a whole nother discussion.

[simonlindholm]

Fixed in #155.