* Add valid field
* Add isNoteDataValid function
* Update _areDefinitionsAddableForcedValue to return proper valid values
* Refactor isAnkiConnected check
* Force canAdd to false if not valid
* 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
* Create Logger class and log instance
* Replace yomichan.logWarning with log.warn
* Replace yomichan.logError with log.error
* Replace yomichan.log with log.log
* Update the Yomichan class to use the global log object
* Update lint rules
* Move fg/js/frame-ancestry-handler.js to js/comm/frame-ancestry-handler.js
* Move fg/js/frame-offset-forwarder.js to js/comm/frame-offset-forwarder.js
* Move fg/js/dom-text-scanner.js to js/dom/dom-text-scanner.js
* Move fg/js/text-source-element.js to js/dom/text-source-element.js
* Move fg/js/text-source-range.js to js/dom/text-source-range.js
* Move fg/js/float-main.js to js/display/popup-main.js
* Move fg/js/content-script-main.js to js/app/content-script-main.js
* Move fg/js/frontend.js to js/app/frontend.js
* Move fg/js/popup-factory.js to js/app/popup-factory.js
* Move fg/js/popup-proxy.js to js/app/popup-proxy.js
* Move fg/js/popup-window.js to js/app/popup-window.js
* Move fg/js/popup.js to js/app/popup.js
* 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
