Modified onexxx handlers to unbind themselve when executed; Reintroduced event fixes (and added some more comments)

Fixed and improved jQuery's event system: The target property of the event object is now fixed (IE and Safari), bind() accepts now a third parameter "amount" to run the function only the specified number of times, oneclick etc. uses this new bind - it removes the handler when it is not necessary anymore, therefore providing better performance, see accordion for test/demo ( http://joern.jquery.com/accordion/accordion.html )

Modified core and form test suites to use a single stylesheet; Modified form.js to use :submit instead of [@type=submit] and :image...

Cleaned up jQuery.clean method (Thanks Dave Methvin)

Fixed previous tests for 193 and 170.

Removed unused line of code from fx.

Added fix for jQuery.extend( Object, null || undefined ) lapsing back to just jQuery.extend( Object ).

Fix for #265: Initialize defaults for global and timeout properly when $.ajax is called internally (argument list instead of hash)

Fixed #216, added several tests for ajax module and fixed more stuff revealed by those; Reverted Johns change for each (changeset 433), caused way too much trouble

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