Fix README.md and locales

[athdesk]

Adds missing languages' support in README.md and fixes a typo in the italian locale

[athdesk]

closing due to pull request being incomplete, didn't test the locale

[athdesk]

everything works now apparently, might have been a problem with my xcode instance
i'm not sure if this works for everyone, so please test this before pulling

[simonmeusel]

Thank you for fixing the README.md and the Itatlian lanuage.

But you also changed the formatting of one JSON file and changed the .png files. Please revert those changes.

Alternatively, I can pick out the changes and put them in a separate commit, if you want.

This PR contains a lot of different changes. In general it is recommended to only change specific parts in one PR.

[athdesk]

I reverted everything in the AppIcon.appiconset package, which were the changes to Contents.json and the image files
I should really have commited just README and the localisation files, instead i did git add . thinking it wouldn't affect the icon-related files, as all i did with them was replacing the corrupted ones that were cloned with copies from the github web service, ultimately i'm sorry for the inconvenience, and now the pull request is much cleaner

[simonmeusel]

Thank you. This is going to be in the next release.