Improved Polish language support

[r0d0dendr0n]

Description

Added a language strings for extracting dates from constant relative date strings like "today".
Adds a reasonably good Polish language support for weather related queries.

Type of PR

If your PR fits more than one category, there is a high chance you should submit more than one PR. Please consider this carefully before opening the PR.
Either delete those that do not apply, or add an x between the square brackets like so: - [x]

• Bugfix
• Feature implementation
• Refactor of code (without functional changes)
• Documentation improvements
• Test improvements

Testing

Set Mycroft to Polish and ask "Jaka będzie jutro pogoda" or "czy przyda mi się parasol w przyszły weekend".

Documentation

There is no documentation for this skill.

CLA

My CLA has already been submitted.

[r0d0dendr0n]

It's worth noting that one needs to invoke: mycroft-config set load_langs_on_demand True for lingua_franca to properly load English, along with your primary non-English language. Otherwise you will get a an exception from lingua_franca. Maybe there are other ways that I am not aware of.

[r0d0dendr0n]

Actualy you need to manualy set load_langs_on_demand = True on config.py of lingua_franca and restart Mycroft. Kind of sucks that lingua_franca seems borked for now.

[krisgesling]

I think for mycroft-core we should be loading English for all installs, simply because that has been a long term assumption in it's development.

The intention is to have this occur in core as that's the code base requiring English, rather than require anyone using LF load English when they have no reason to need it.

Again thanks for flagging it