Changes to language sourcing

[Anadroid]

No description provided.

[Anadroid]

This PR:

1. changes gatsby-node.js so that:

   • reference url contain the language code to be able to source english pages if there is missing translation
   • change path to refPath because there is already a path variable

2. change to SubcategoryList.js link to show to remove the language code from the file name in the url

3. changes to examples.js and tutorials.js (same change), example-template.js and tutorial-template.js (same change), and index-ref-template.js so that the english page is shown if there is no translation

4. adds files to check if localized pages work when there is translated content as well as when there isn't:

   • Client_active().de.json and Client_available().de.json to the net library
   • folder coordinate-system-and-shapes and index.md to the tutorials

[runemadsen]

This is beautiful! Merging in.