Add limit
My bad, didn't see this on the open dataset list. Closing this since it overlaps with PR#1256
This PR adds [LiMiT](https://github.com/ilmgut/limit_dataset), a dataset for literal motion classification/extraction by [Manotas et al., 2020](https://www.aclweb.org/anthology/2020.findings-emnlp.88.pdf).