Fix ACP login in ACP require mode
Add QR as dependency
Generate QR code w/o external services

Fixes #11
Add missing language items
Clean up blacklisted code
Add recaptcha to 2Factor-Auth (brute force protection)

Fixes #6
Ask only once every `TWOFA_REASK_PERIOD` days
Always recheck in ACP
Remove `hash_hmac` PHP requirement
Bump version number and fix update instructions