Description

I have added a new model named HypAR, a new example file for HypAR, and made edits to Lightgcn.

For HypAR I've created the recom_hyper file, requirements.txt and requirements_cu116.txt.
The example file runs the method on the Cellphone dataset. As this is not part of Cornac, I simply define the methods for creating the dataset directly in the example. The parameters for HypAR are found on the validation set.

For LightGCN I have (see commit 1799bf8):

• Removed normalization for layers, not used for lgcn.
• Fixed sum weight constant to num layers instead of cur layer index.
• Allow lgcn to take blocks.
• Fixed requirement error caused by newer dgl versions.
• Moved edge normalization to graph for easier use.
  Without these LightGCN wouldn't perform as required.

Todo: Add reference to paper once publicised in readme.

Checklist:

• I have added tests.
• I have updated the documentation accordingly.
• I have updated README.md (if you are adding a new model).
• I have updated examples/README.md (if you are adding a new example).
• I have updated datasets/README.md (if you are adding a new dataset).