only compare host:port in Websocket.check_origin

don't include protocol

- matches tornado's own behavior
- avoids incorrect 403 in http-behind-https proxy situations.
better log messages when rejecting cross-origin requests
rename webapp_settings to tornado_settings

deprecate `webapp_settings`

More informative name to those who would actually use this feature.
It sets overrides for the tornado global `settings` object.
Refactor inputhook to allow easy extension.
Add module-level access to register method
Allow registering external event loops to integrate with kernel
Add docs about extending GUI integration
Merge pull request #6480 from minrk/origin-check-no-proto

only compare host:port in Websocket.check_origin
Deprecation warnings for enable_* functions in inputhook

Also, update examples to not use these
Merge pull request #6491 from minrk/tornado_settings

rename webapp_settings to tornado_settings
Add note about function deprecations in whatsnew doc
Merge pull request #5666 from takluyver/inputhook-extensible

Refactor inputhook to allow easy extension
%gui qt5