handle string ffmpeg input (#2064)

* handle string ffmpeg input

* rename stuff for new purpose

* file prefix isn't needed

* pass tests

* remove dumb spaces in dispatcher docs

src/client/voice/dispatcher/BroadcastDispatcher.js

@@ -1,4 +1,3 @@
-const Collection = require('../../../util/Collection');
 const StreamDispatcher = require('./StreamDispatcher');
 
 /**

src/client/voice/dispatcher/StreamDispatcher.js

@@ -147,7 +147,7 @@ class StreamDispatcher extends Writable {
 
   /**
    * Sets the expected packet loss percentage if using a compatible Opus stream.
-   * @param {number} value between 0 and 1 
+   * @param {number} value between 0 and 1
    * @returns {boolean} Returns true if it was successfully set.
    */
   setPLP(value) {
@@ -158,7 +158,7 @@ class StreamDispatcher extends Writable {
 
   /**
    * Enables or disables forward error correction if using a compatible Opus stream.
-   * @param {boolean} enabled true to enable 
+   * @param {boolean} enabled true to enable
    * @returns {boolean} Returns true if it was successfully set.
    */
   setFEC(enabled) {