Scoping issue

```
What steps will reproduce the problem?
1. Do two parallel calls with microAjax
2. Expect two different callbacks
3. Just the last one returns

What is the expected output? What do you see instead?
Two callbacks with different scoping

What version of the product are you using? On what operating system?
Any browser

Please provide any additional information below.

Either use "new microAjax( .. , .. );" (change the example) to provide
individual scopes, or use a local variable like this:
https://gist.github.com/2420333

Works perfectly otherwise...

```

Original issue reported on code.google.com by `possan2` on 19 Apr 2012 at 11:23