Expose some types

[pedrodurek]

Closes #1869

Checklist

• only relevant code is changed (make a diff before you submit the PR)
• run tests npm run test
• tests are included
• commit message and code follows the Developer's Certification of Origin

Checklist (for documentation change)

• only relevant documentation part is changed (make a diff before you submit the PR)
• motivation/reason is provided
• commit message and code follows the Developer's Certification of Origin

[coveralls]

Coverage remained the same at 91.157% when pulling 51efb4d on pedrodurek:expose-extra-types into 77da0d1 on i18next:master.