Singularize corpora

[ErikEJ]

[TestCase("corpora", "corpus")] - but get corpora

[sarathkcm]

Currently corpus is being pluralized into corpuses. While both corpora and corpuses both are correct, I think adding an irregular rule to pluralize corpus into corpora by default will solve this problem.

I will raise the same issue in the original java-script library, and will follow the same approach they follow, as we plan to keep the behavior same as the original library.

[sarathkcm]

Raised issue here