Added Visualized song player and required playlist modifications (untested).

Class names and respective file names refactored.

Added song player for basic playlist management and playback.

Added support for visualizers per song in the playlist.

Created a visualizer update manager that acts as a splitter for all the bins and their updates.

Fixed potential bugs.

src/player/SongPlaylist.js

@@ -48,14 +48,13 @@ export default class SongPlaylist {
         if (index >= this._list.length) {
             return null;
         }
-        let removed = this._list.splice(index, 1);
+        let removed = this._list.splice(index, 1)[0];
         if (removed.length > 0) {
             return removed[0];
         }
     }
 
     findSongIndex(name) {
-        // TODO: Could probably be optimized.
         return this._list.findIndex((item) => item.getDisplayName() == name);
     }