Implicit key splay tree

[kalabukdima]

Hello. I have seen your implementation of splay tree data structure. I want to propose quiet different data structure - splay tree with implicit key (not sure about naming). It doesn't support finding elements by key. Instead, it allows to emulate sequence of elements and supports concatenating, splitting and reversing with log(n) complexity in average.
For better explanation refer to this post.
You can find my implementation here.
It is written for c++14 and with Google style guide. I can fix it and create PR if you are interested.

[moghya]

@kalabukdima sorry for late reply. I went through your PR and thanks for it. Please consider requested changes.
Thanks 👍