Translate Extension: Add an "original language" argument

[apple502j]

Expected Behavior

It should have "original language".

For example: (Star is what it returns now)
湯 (Japanese: hot water Chinese: soup ⭐ )
billion (English: 100,000,000 ⭐ German: 1,000,000,000,000)
gift (English: similar to present ⭐ German: poison)

Actual Behavior

See the star above

Steps to Reproduce

Translate these words: Do at both Scratch and Google to check difference
湯 - Check 🇯🇵 and 🇨🇳
billion - Check 🇬🇧 and 🇩🇪
gift - Check 🇬🇧 and 🇩🇪

Operating System and Browser

Windows 7 Home Premium 64bit SP1
Firefox 60.0.1

⚠️ Note: This may require to change the API