Separation of translation file into several smaller ones.

Fixes #142 (closed)

Adds a tiny CLI tool to check what strings are missing in given language compared to English (/src/i18n/compare.js) usage is within the script as well it prints it out when invoked without arguments.

Separated all the languages except for:

• de
• oc
• pt
• eo

Since they have MRs pending for them. I tried merging !293 (merged) into this branch and it went without conflicts.