Feature request: Custom selection of several different categorys

[java-py-c-cpp-js]

Please include a possibility to select several different categorys at once.

[trytonlux]

One of the limitations of the third party API I am using is that I can only request 1 category at a time.

But it would be easy enough to allow selecting multiple categories and then make multiple requests.

[trytonlux]

Thanks to insight from @lgommans, the next release will include a local copy of the database.

This will remove any limitations of the API, making this feature easier to add.