Complete overhaul of the Ajax test suite, it's now passing in all browsers. In order...

Complete overhaul of the Ajax test suite, it's now passing in all browsers. In order to achieve this I had to fix a numbe
r of bugs in the suite itself, along with other random bugs that popped up. The following bugs were resolved along the wa
y: #1236 (.extend() keeps processing when it hits nulls), #1028 (.extend() now works recursively), #1080 ($.get no longer
 overwrites the data parameter), #1210 (Creating script and link tags now work), and #1463 (jQuery.global has been re-too
led to no longer leak memory and slow things down).