LAM 6.7 with YubiKey 2FA and extended Bind DLZ support

• Added YubiKey as 2-factor authentication provider
• Support logging to remote syslog server
• PHP 7.3 support
• LAM Pro:
  • Allow to mark text and text area fields as required
  • New self service fields:
    • Mail routing
    • Windows proxy addresses + mail alias
    • Shadow account expiration date
    • Unix and group of names memberships
  • Base URL for emails in self service can be configured in self service profile
  • Bind DLZ: support DNAME+XFR records and descriptions in records (requires latest LDAP schema)
  • Cron jobs: added Shadow account expiration notification job
• Fixed bugs:
  • Allow tree-only configurations without any other tab