Major refactoring of async code

The result is correct handling of tiddlers being overwritten within
recipes.

node_modules/async/deps/nodeunit.css

@@ -1,70 +0,0 @@
-/*!
- * Styles taken from qunit.css
- */
-
-h1#nodeunit-header, h1.nodeunit-header {
-    padding: 15px;
-    font-size: large;
-    background-color: #06b;
-    color: white;
-    font-family: 'trebuchet ms', verdana, arial;
-    margin: 0;
-}
-
-h1#nodeunit-header a {
-    color: white;
-}
-
-h2#nodeunit-banner {
-    height: 2em;
-    border-bottom: 1px solid white;
-    background-color: #eee;
-    margin: 0;
-    font-family: 'trebuchet ms', verdana, arial;
-}
-h2#nodeunit-banner.pass {
-    background-color: green;
-}
-h2#nodeunit-banner.fail {
-    background-color: red;
-}
-
-h2#nodeunit-userAgent, h2.nodeunit-userAgent {
-    padding: 10px;
-    background-color: #eee;
-    color: black;
-    margin: 0;
-    font-size: small;
-    font-weight: normal;
-    font-family: 'trebuchet ms', verdana, arial;
-    font-size: 10pt;
-}
-
-div#nodeunit-testrunner-toolbar {
-    background: #eee;
-    border-top: 1px solid black;
-    padding: 10px;
-    font-family: 'trebuchet ms', verdana, arial;
-    margin: 0;
-    font-size: 10pt;
-}
-
-ol#nodeunit-tests {
-    font-family: 'trebuchet ms', verdana, arial;
-    font-size: 10pt;
-}
-ol#nodeunit-tests li strong {
-    cursor:pointer;
-}
-ol#nodeunit-tests .pass {
-    color: green;
-} 
-ol#nodeunit-tests .fail {
-    color: red;
-} 
-
-p#nodeunit-testresult {
-    margin-left: 1em;
-    font-size: 10pt;
-    font-family: 'trebuchet ms', verdana, arial;
-}