add new episodes to library view, code cleanup

src/App.vue

src/components/Header.vue

src/components/ItemGrid.vue

src/components/ItemSlider.vue

src/components/LoadMore.vue

src/store/episode.js

src/store/show.js

src/views/Browse.vue

src/views/BrowseAll.vue

src/views/Library.vue

src/views/Listening.vue