streaming output data with drain detection support

- other stuff x.x

zefie_wtvp_minisrv/WTVShared.js

@@ -94,6 +94,16 @@ class WTVShared {
         return path;
     }
 
+    /**
+     * Returns a percentage
+     * @param {number} partialValue
+     * @param {number} totalValue
+     * @returns {number} percentage
+     */
+    getPercentage = function (partialValue, totalValue) {
+        return Math.floor((100 * partialValue) / totalValue);
+    }
+
     /**
      * If the file ends with .gz, remove it
      * @param {string} path