Added 'autoDelete' setting. Probably needs some more work.

If true, and if this is our first input, and if the users types
something that would otherwise have been appended to the default
text, then the default text is deleted first.

exec/load/typeahead.js

@@ -238,6 +238,8 @@ var Typeahead = function (options) {
         attr: console.attributes,
         focus: true,
         maxResults: 0,
+        autoDelete: false,
+        gotInput: false,
     };
 
     var display = {
@@ -460,6 +462,10 @@ var Typeahead = function (options) {
                 }
                 break;
             default:
+                if (properties.autoDelete && !properties.gotInput) {
+                    properties.text = '';
+                    properties.position = 0;
+                }
                 if (properties.text.length === properties.len) break;
                 key = strip_ctrl(key);
                 if (properties.position !== properties.text.length) {
@@ -476,6 +482,7 @@ var Typeahead = function (options) {
                 change = true;
                 break;
         }
+        properties.gotInput = true;
         if (change) {
             display.inputFrame.clear();
             display.inputFrame.putmsg(properties.text);