Bug fixes & more features

• Update to libdot 1.15. Some standards fixes.
• Update to hterm 1.66. Unicode rendering fixes, mouse fixes, custom
  notification support, and character map robustification.
• Fix handling of custom --ssh-agent when using --config=google.
• Stop enabling ssh-agent forwarding by default for non-google configs.
• Document support for cycling input methods (in CrOS).
• Refresh translations everywhere!
• Document more relay options.