Qnap [ Gotty ] [ 1.5.0 ] light WebSSH

Pass BUILD_OPTIONS to gox, too, so release artifacts have version info included.
Update xterm.js 2.7.0 => 4.11.0
Lots of clean up.

Links in the tty are now clickable.
Use WebGL for rendering by default.
Ensure authentication (TLS or Basic auth) remain enabled even if some of the options are only given in config files Thanks, @devanlai!
Fix typo in README.md Thanks, @prusnak!
Add arm64/Linux build. Thanks for the suggestion, @nephaste!

It's been a while since our last release. The most interesting new thing is the file upload/download mechanism. Any ZModem transfer (the sz and rz commands from lrzsz) will trigger a popup where you can accept or reject the file transfer.

Otherwise, it's all bug fixes and behind the scenes improvements.

Add @hardliner66 as a contributor (1ca998e)
Add @jkandasa as a contributor (cd23910)
Add backend tests (603c650)
Add generated data to git (a9fbc07)
add quiet flag to disable logging (4109b11)
Add references to @yudai (bffd821), closes #8
Add rule to build gotty.js.map (82c3acf)
Apply font size and family in xterm (f157dbe), closes #21
Avoid HTTP 401 error on manifest.json due to CORS (817b5c8)
Bump browserslist from 4.16.4 to 4.16.6 in /js (8deba62)
Disable arg passing by default (5c8eb10), closes #17
Do not include ALL of bootstrap (b63ea16)
Ensure defaults for booleans is set correctly (28f8e61), closes #16
Fix existing tests (d674aa1), closes #13
Fix warnings from Markdown linter (aa86a34)
go fmt (dcb153c)
Improve webtty test coverage (f61763f)
Make client request base64 encoding (dd3603c)
Make sure we read the full message (1eed97f)
Publish artifacts on push to master (6c62ab7)
Remove hterm (163fd05)
Run tests on push (55674f1)
Run tests on push to all branches (679a324)
update go version in Dockerfile (fd2fb99)
Update js dependencies (26fc412)
Update xterm.js and other js libs (81afdc7), closes #18
Use bootstrap components for up- and downloads (7f05f2f)
Use Go's built-in embed mechanism (f66f0d0), closes #7
feat(zmodem): Allow file uploads/downloads (782991c)