* Update settings controller to consistently initialize
* Allow profile index to be reset if an error occurs
* Update message handler to be async
* Fix error when deleting the current profile
* Move some common functionality
* Move setupEnvironmentInfo into ExtensionContentController
* Move background/environment.js to extension/environment.js
* Update environment info to return the 'safari' browser
* Fix popup display on Safari
* Update environment assignment
* Add data-loading-stalled property when loading takes longer than expected
* Add notification when loading has stalled
* Allow getDictionaryInfo invocation on non-privileged contexts
* Update _validatePrivilegedMessageSender
* Don't listen to 'voiceschanged' event unless addEventListener is present
Also expose an event
* Add double-down-chevron.svg
* Add options
* Update dictionary importers
* Update settings
* Add support for collapsible definitions
* Improve case when there is a very small amount of overflow
* Fix incorrect enabled state of newly imported dictionaries
