fix map function and benchmark tests

desktop/sources/scripts/library.js

@@ -377,11 +377,8 @@ function Library (ronin) {
     }
   }
 
-  this.map = async (arr, fn) => { // Run a function on each element in a list.
-    for (let i = 0; i < arr.length; i++) {
-      const arg = arr[i]
-      arr[i] = await fn(arg)
-    }
+  this.map = (arr, fn) => { // Run a function on each element in a list.
+    return Promise.all(arr.map(fn)).then( result => { return result } )
   }
 
   this.filter = (arr, fn) => { // Remove from list, when function returns false.