Add datasets from https://github.com/Softcatala/nmt-softcatala

[marco-c]

Most of them are available already in OPUS, but some of them aren't.
For example, MemoriesProjectesLliures (https://github.com/Softcatala/parallel-catalan-corpus/tree/master/eng-cat) doesn't seem to be available as far as I can see.

CC @jordimas