Add MurP

[cthoyt]

On which paper(s) is your requested model based.

Originally proposed in https://arxiv.org/abs/1905.09791
More thoroughly investigated in https://openreview.net/forum?id=gLWj29369lW

List the original and other existing implementations of this model
Please provide links to the original implementation and an as comprehensive as possible list about other implementations
of this model.

Original Implementation: https://github.com/ibalazevic/multirelational-poincare

Relevance of this model

Another non-euclidean model, related to #310

TODOs

This issue will also require the implementation of the Reimann Optimizer and a new system for tagging different parameters for how they should be optimized