translation: break strings out so they can be fed into CrowdIn

[jaustin]

For the main microbit.org site we are using CrowdIn for translation. It would be good if the strings for the PythonEditor were broken out in such a way that we could translate this editor for each country at the same time as we translate the main site.

There are lots of enthusiastic translators around micro:bit so this should really be a case of making it easy for them :)

https://crowdin.com/

[jaustin]

@JakubLenski it's awesome to be able to close this 2 year old issue thanks to all the work you've done in #151. Hooray!