Delete Spanish (AR) translation

It won’t be updated, and contains typos, mistranslations (such as “Aproximadamente” instead of “Acerca de” for “About”), the tone is wrong…
Closes issue 4005.
Merge pull request #2625 from Fitoschido/patch-1

Delete Spanish (AR) translation
Improved embedded cover handling for Ogg METADATA_BLOCK_PICTURE
Make sure that we feed set_url() with a QUrl from an UTF-8 encoded string.