Beatport UI Tweaks

Small quality-of-life tweaks for beatport.com, each one switchable in the popup (Alt+Shift+B). - Remember last played: scrolls back to the track you played last when you return to a list, and the "Last played" button next to the pager finds the page that track has moved to since, for your per-page setting - Highlight playing track: outlines the row that is playing - Keyboard playback: A plays the previous track, Z the next one - Camelot key: the Camelot code of every track in Camelot wheel colors, lined up in one column, next to the key on track pages and in the player - Recently used playlists first: the playlists you added tracks to lead the "add to playlist" dialog, latest first - Playlist filter: a search box in the "add to playlist" dialog, the list narrows as you type and loads all your playlists Nothing leaves your browser: settings are kept in Chrome's extension storage, the playlist history in the page's local storage. Beatport's own catalog API is asked where a track is, with the same access the page has.