Improve Unicode handling

• lib.TestManager.Log completely rewritten for better capturing & use.
• Add a bin/load_tests.sh helper for quickly launching the tests.
• New lib.f.randomInt helper for integer ranges.
• lib.wc.substr now includes trailing combining characters.

Improve Unicode handling

• Add ids to more internal elements for debugging.
• Disable drag & drop of text/content.
• Fix helper scripts/docs to use POSIX portable \033 instead of \e with printf.
• Drop support for old Chrome <21 versions with storage setup.
• Rewrite Unicode processing to avoid stripping combining characters.
• Make encoding state internal and add setEncoding callback to the API.
• Stop matching 8-bit control codes in utf8 mode.

Minor improvements

• Update to hterm 1.69. Improve cursor tracking and add pref for default encoding.
• Rework user ssh command line processing.

Improve cursor positioning

• Add a pref for default terminal encoding.
• Add a helper/document for the new notification position.
• Switch cursor positioning to use CSS vars.

New feature polish

• Update to hterm 1.68. Various fixes for new features, and make accidental
  character map transitions more robust.
• Shrink & shift connection dialog to not take up so much space.
• Rework passing of subsystem down to the OpenSSH NaCl.

New feature polish, and robustify character maps

• Restore native pasting as a fallback for the open web.
• Change default G1 character map to US/ASCII.
• Change DECCKM mouse wheel events to default to off.
• Add support for DOCS for transitioning to UTF-8 (ESC+%).

New feature polish

• Fix identity dropdown list display.

New feature polish

• Update to hterm 1.67. Various fixes for new features.
• Tweak relay options for .c.googlers.com domains.

New feature polish

• Open links on macOS via cmd+click.
• Fix URL opening for Chrome v2 apps.
• Support disabling DECCKM mouse wheel events.

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.