New feature

• Add dropdown language selector in checkout v2 @dennisreimann

Bug fix

• Avoid crash when some plugins are installed (#4725)
• Greenfield: Do not crash if create API key is called on a non-existant user (Fix #4731)

Improvements

• Remove superflous punctuation in some translations
• Update Polski translation
• Greenfield: Routes accepting a userId can now also accept userEmail (#4732)