sort translation strings and eliminate duplicates

Is there a tool to support translating?  I tried to use i18next-webtranslate but I couldn't get grunt working. That project hasn't been updated for two years, so I suppose it is abandoned.

I ended up doing the translation by hand. My first step was to sort the labels and eliminate duplicates which is the reason for this pull request.

If this is not the way to go, because I can imagine that the json is generated by some script or function although I couldn't find it (???), please let me know how I should proceed to generate the es json file and keep it in sync with the en json file similar to what we did with gettext.