* Add url/voice options to audio sources
* Add help for TTS
* Remove old settings
* Update tests
* Update use of audio source URL
* Improve labels for sources with the same type
* Update how options are updated and stored in DisplayAudio
* Add source list
* Improve menus for custom json
* Clear cache after options update
* Move function
* Update public API
* Simplify playing audio from a specific source
* Simplify audio list
* Refactor audio source usage
* Refactoring
* Refactor argument names
* Fix incorrect source usage
* Remove unused
* Remove return value
* Simplify details
* Simplify Anki card audio details
* Update the data that is passed to AudioDownloader
* Simplify schema handling
* Remove unnecessary details
* Move sources to the end of audio options object
* Add custom-json audio source type
* Add support for downloading custom-json
* Remove customSourceType
* Expose modifier keys
* Add updateMenuItems
* Don't close menu if shift key is held
* Add _createMenuItems
* Simplification
* Maintain a list of open popup menus
* Expose expression/reading
* Reuse existing items
* Update menu after a cache update
* Update menu position
* Add card icon to audio menu items
* Update cache data format
* Create _getCacheItem
* Add _playAudioFromSource function
* Implement default card audio info
* Specify exact audio to download when an override is assigned
* Abstract using _getMenuItemSourceInfo
* Update downloadability check
* Update the main audio menu buttons to also assign the default source
* Move mixed/js/core.js to js/core.js
* Move mixed/js/yomichan.js to js/yomichan.js
* Move mixed/js/timer.js to js/debug/timer.js
* Move mixed/js/hotkey-handler.js to js/input/hotkey-handler.js
* Move mixed/js/hotkey-help-controller.js to js/input/hotkey-help-controller.js
* Move mixed/js/hotkey-util.js to js/input/hotkey-util.js
* Move mixed/js/audio-system.js to js/input/audio-system.js
* Move mixed/js/media-loader.js to js/input/media-loader.js
* Move mixed/js/text-to-speech-audio.js to js/input/text-to-speech-audio.js
* Move mixed/js/comm.js to js/comm/cross-frame-api.js
* Move mixed/js/api.js to js/comm/api.js
* Move mixed/js/frame-client.js to js/comm/frame-client.js
* Move mixed/js/frame-endpoint.js to js/comm/frame-endpoint.js
* Move mixed/js/display.js to js/display/display.js
* Move mixed/js/display-audio.js to js/display/display-audio.js
* Move mixed/js/display-generator.js to js/display/display-generator.js
* Move mixed/js/display-history.js to js/display/display-history.js
* Move mixed/js/display-notification.js to js/display/display-notification.js
* Move mixed/js/display-profile-selection.js to js/display/display-profile-selection.js
* Move mixed/js/japanese.js to js/language/japanese-util.js
* Move mixed/js/dictionary-data-util.js to js/language/dictionary-data-util.js
* Move mixed/js/document-focus-controller.js to js/dom/document-focus-controller.js
* Move mixed/js/document-util.js to js/dom/document-util.js
* Move mixed/js/dom-data-binder.js to js/dom/dom-data-binder.js
* Move mixed/js/html-template-collection.js to js/dom/html-template-collection.js
* Move mixed/js/panel-element.js to js/dom/panel-element.js
* Move mixed/js/popup-menu.js to js/dom/popup-menu.js
* Move mixed/js/selector-observer.js to js/dom/selector-observer.js
* Move mixed/js/scroll.js to js/dom/window-scroll.js
* Move mixed/js/text-scanner.js to js/language/text-scanner.js
* Move mixed/js/cache-map.js to js/general/cache-map.js
* Move mixed/js/object-property-accessor.js to js/general/object-property-accessor.js
* Move mixed/js/task-accumulator.js to js/general/task-accumulator.js
* Move mixed/js/environment.js to js/background/environment.js
* Move mixed/js/dynamic-loader.js to js/scripting/dynamic-loader.js
* Move mixed/js/dynamic-loader-sentinel.js to js/scripting/dynamic-loader-sentinel.js
